Welcome to the MongoDB Tutorials. The objective of these tutorials is to get an in-depth understanding of <a href="mongodb-database" target="_blank" rel="noopener">MongoDB Database</a>. In these tutorials, we will cover various MongoDB functions with examples. The tutorial starts with an overview of MongoDB, Installation of MongoDB and later we will cover various functions such as find, query, update and delete. Apart from these we will also cover the Performance and Tuning aspects of MongoDB.
In addition to these tutorials, we will also cover common issues, Interview questions and How To's of MongoDB.
<h2 style="text-align: justify;">What is MongoDB?</h2>
<a class="zem_slink" title="MongoDB" href="http://en.wikipedia.org/wiki/MongoDB" target="_blank" rel="noopener wikipedia">MongoDB</a> is a powerful, flexible, and scalable data store. It combines the ability to scale out with many of the most useful features of relational databases, such as secondary indexes, range queries, and sorting. MongoDB is also incredibly featureful: it has tons of useful features such as built-in support for MapReduce-style aggregation and geospatial indexes.
There is no point in creating a great technology if it&rsquo;s impossible to work with, so a lot of effort has been put into making MongoDB easy to get started with and a pleasure to use. MongoDB has a developer-friendly data model, administrator-friendly configuration options, and natural-feeling language APIs presented by drivers and the database shell. MongoDB tries to get out of your way, letting you program instead of worrying about storing data.
<h3>Index</h3>
<ul>
<li><a href="where-clause-in-mongodb/">Where Clause in MongoDB</a></li>
<li><a href="sort-document-mongodb/">How to sort document in MongoDB</a></li>
<li><a href="modify-and-find-mongodb/">Find and Modify in MongoDB</a></li>
<li><a href="how-to-search-document-in-mongodb/">How to Find/Search Document in MongoDB</a></li>
<li><a href="using-select-mongodb/">Using Select in MongoDB</a></li>
<li><a href="mongodb-interface/">MongoDB Interface</a></li>
<li><a href="collections-in-mongodb/">Collections in MongoDB</a></li>
<li><a href="deleteremove-collection-mongodb/">Delete/Remove collection in MongoDB</a></li>
<li><a href="mongodb-index/">MongoDB Index</a></li>
<li><a href="insert-document-mongodb/">How to insert document in MongoDB</a></li>
<li><a href="mongodb-database/">MongoDB Database</a></li>
<li><a href="mongodb-data-types">MongoDB Data Types</a></li>
<li><a href="installation-of-mongodb/">How to install MongoDB</a></li>
<li><a href="delete-document-mongodb/">How to delete document in MongoDB</a></li>
<li><a href="update-document-mongodb/">How to Update document in MongoDB</a></li>
</ul>
<h2 style="text-align: justify;">MongoDB Overview</h2>
MongoDB is a cross-platform, document-oriented database that provides, high performance, high availability, and easy scalability. MongoDB works on the concept of collection and document.
<h2 style="text-align: justify;">Database</h2>
The database is a physical container for collections. Each database gets its own set of files on the file system. A single MongoDB server typically has multiple databases.
<h2 style="text-align: justify;">Collection</h2>
A collection is a group of MongoDB documents. It is the equivalent of an <a href="sql-rdbms-concepts" target="_blank" rel="noopener">RDBMS </a>table. A collection exists within a single database. Collections do not enforce a schema. Documents within a collection can have different fields. Typically, all documents in a collection are of similar or related purposes.
<h2 style="text-align: justify;">Document</h2>
A document is a set of key-value pairs. Documents have a dynamic schema. Dynamic schema means that documents in the same collection do not need to have the same set of fields or structures, and common fields in a collection's documents may hold different types of data.
Below given table shows the relationship of RDBMS terminology with <a href="mongodb-data-types" target="_blank" rel="noopener">MongoDB</a>
<img class="alignnone size-full wp-image-17763" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2016/05/Screenshot_112.png" alt="Screenshot_1" width="801" height="336" />
Sample document
Below given example shows the document structure of a blog site which is simply a comma-separated key-value pair.
<pre style="text-align: justify; padding-left: 30px;">{
_id: ObjectId(7df78ad8902c)
title: 'MongoDB Overview',
description: 'MongoDB is no sql database',
by: 'tutorials point',
url: 'http://www.tutorialspoint.com',
tags: ['mongodb', 'database', 'NoSQL'],</pre>
<pre style="text-align: justify; padding-left: 30px;">likes: 100,
comments: [
{
user:'user1',
message: 'My first comment',
dateCreated: new Date(2011,1,20,2,15),
like: 0
},
{
user:'user2',
message: 'My second comments',
dateCreated: new Date(2011,1,25,7,45),
like: 5
}
]
}</pre>
<pre style="text-align: center;">Interested in mastering MongoDB Training? Enroll now for FREE demo on <a href="https://tekslate.com/mongodb-training/" target="_blank" rel="noopener">MongoDB Training</a>.</pre>
_id is a 12 bytes hexadecimal number which assures the uniqueness of every document. You can provide _id while inserting the document. If you didn't provide then MongoDB provides a unique id for every document. These 12 bytes first 4 bytes for the current timestamp, the next 3 bytes for machine id, the next 2 bytes for process id of the MongoDB server, and the remaining 3 bytes are simple incremental value.
<h2 style="text-align: justify;">MongoDB Advantages</h2>
Any relational database has a typical schema design that shows the number of tables and the relationship between these tables. While in MongoDB there is no concept of relationship
<h3 style="text-align: justify;">Advantages of MongoDB over RDBMS</h3>
-Schemaless: MongoDB is a document database in which one collection holds different documents. The number of fields, content, and size of the document can differ from one document to another.
-Structure of a single object is clear
-No complex joins
-Deep query-ability. MongoDB supports dynamic queries on documents using a document-based query language that's nearly as powerful as<a href="sql-tutorials" target="_blank" rel="noopener"> SQL</a>
-Tuning
-Ease of scale-out: MongoDB is easy to scale
-Conversion/mapping of application objects to database objects not needed
-Uses internal memory for storing the (windowed) working set, enabling faster access of data
<h3 style="text-align: justify;">Why should use MongoDB</h3>
Document Oriented Storage: Data is stored in the form of JSON style documents
Index on any attribute
Replication &amp; High Availability
Auto-Sharding
Rich Queries
Fast In-Place Updates
Professional Support By MongoDB
<h3 style="text-align: justify;">Where should use MongoDB?</h3>
Big Data
Content Management and Delivery
Mobile and Social Infrastructure
User Data Management
Data Hub
<h1 style="text-align: justify;">&nbsp;</h1>

MongoDB Tutorial | Learn MongoDB Online in a Simple Way

MongoDB Tutorials

mongodb-tutorials

MongoDB Interview Question and Answers

mongodb-interview-questions-answers

<h2 style="text-align: justify;">MongoDB</h2>
<h3 style="text-align: justify;">Updating Documents </h3>
Once a <a class="zem_slink" title="Document" href="http://en.wikipedia.org/wiki/Document" target="_blank" rel="noopener wikipedia">document</a> is stored in the <a href="https://tekslate.com/mongodb-training/">database</a>, it can be changed using the update method. update takes two parameters: a query document, which locates documents to update, and a <a class="zem_slink" title="Grammatical modifier" href="http://en.wikipedia.org/wiki/Grammatical_modifier" target="_blank" rel="noopener wikipedia">modifier</a> document, which describes the changes to make to the documents found.
Updates are atomic: if two updates happen at the same time, whichever one reaches the server first will be applied, and then the next one will be applied. Thus, conflicting updates can safely be sent in rapid-fire succession without any documents being corrupted: the last update will &ldquo;win.&rdquo;
<h3 style="text-align: justify;">Document Replacement</h3>
The simplest type of update fully replaces a matching document with a new one. This can be useful to do a dramatic schema migration. For example, suppose we are making major changes to a user document, which looks like the following:
<pre style="text-align: justify;">{
"_id" : ObjectId("4b2b9f67a1f631733d917a7a"),
"name" : "joe",
"friends" : 32,
"enemies" : 2
}</pre>
We want to change that document into the following:
<pre style="text-align: justify;">"_id" : ObjectId("4b2b9f67a1f631733d917a7a"),
"username" : "joe",
"relationships" :
{
"friends" : 32,
"enemies" : 2
}
}</pre>
We can make this change by replacing the document using an update:
<pre style="text-align: justify;">var joe = db.users.findOne({"name" : "joe"});
joe.relationships = {"friends" : joe.friends, "enemies" : joe.enemies};{
"friends" : 32,
"enemies" : 2
}
joe.username = joe.name;
"joe"
delete joe.friends;
true
delete joe.enemies;
true &gt;
delete joe.name;
true &gt;
db.users.update({"name" : "joe"}, joe);</pre>
Now, doing a find One shows that the structure of the document has been updated. A <a class="zem_slink" title="Mistake (contract law)" href="http://en.wikipedia.org/wiki/Mistake_%28contract_law%29" target="_blank" rel="noopener wikipedia">common mistake</a> is matching more than one document with the criteria and then create a duplicate "_id" value with the second parameter. The database will throw an error for this, and nothing will be changed. For example, suppose we create several documents with the same "name", but we don&rsquo;t realize it:
<pre style="text-align: justify;">db.people.find()</pre>
<pre style="text-align: justify;">{"_id" : ObjectId("4b2b9f67a1f631733d917a7b"), "name" : "joe", "age" : 65},</pre>
<pre style="text-align: justify;">{"_id" : ObjectId("4b2b9f67a1f631733d917a7c"), "name" : "joe", "age" : 20},</pre>
<pre style="text-align: justify;">{"_id" : ObjectId("4b2b9f67a1f631733d917a7d"), "name" : "joe", "age" : 49},</pre>
Now, if it&rsquo;s Joe #2&rsquo;s birthday, we want to increment the value of his "age" key, so we might say this:
<blockquote>
<pre style="text-align: justify;">joe = db.people.findOne({"name" : "joe", "age" : 20});
{
"_id" : ObjectId("4b2b9f67a1f631733d917a7c"),
"name" : "joe",
"age" : 20
}
joe.age++;
db.people.update({"name" : "joe"}, joe);</pre>
</blockquote>
E11001 duplicate key on update
What happened? When you call update, the database will look for a document matching {"name" : "joe"}. The first one it finds will be the 65-year-old Joe. It will attempt to replace that document with the one in the joe variable, but there&rsquo;s already a document in this collection with the same "_id". Thus, the update will fail, because "_id" values must be unique. The best way to avoid this situation is to make sure that your update always specifies a unique document, perhaps by matching on a key like "_id"
<h3 style="text-align: justify;">Using Modifiers</h3>
Usually only certain portions of a document need to be updated. Partial updates can be done extremely efficiently by using <a class="zem_slink" title="Atomicity (database systems)" href="http://en.wikipedia.org/wiki/Atomicity_%28database_systems%29" target="_blank" rel="noopener wikipedia">atomic update</a> <a href="https://tekslate.com/mongodb-tutorials">modifiers</a>. Update modifiers are special keys that can be used to specify complex update operations, such as altering, adding, or removing keys, and even manipulating arrays and embedded documents.
Suppose we were keeping <a class="zem_slink" title="Web analytics" href="http://en.wikipedia.org/wiki/Web_analytics" target="_blank" rel="noopener wikipedia">website analytics</a> in a collection and wanted to increment a counter each time someone visited a page. We can use update modifiers to do this increment atomically. Each <a class="zem_slink" title="Uniform resource locator" href="http://en.wikipedia.org/wiki/Uniform_resource_locator" target="_blank" rel="noopener wikipedia">URL</a> and its number of <a class="zem_slink" title="Page view" href="http://en.wikipedia.org/wiki/Page_view" target="_blank" rel="noopener wikipedia">page views</a> is stored in a document that looks like this:
<pre style="text-align: justify;">{
"_id" : ObjectId("4b253b067525f35f94b60a31"),
"url" : "www.example.com",
"pageviews" : 52
}</pre>
Every time someone visits a page, we can find the page by its URL and use the "$inc" modifier to increment the value of the "pageviews" key.
<pre style="text-align: justify;">&gt; db.analytics.update({"url" : "www.example.com"},
... {"$inc" : {"pageviews" : 1}})
Now, if we do a find, we see that "pageviews" has increased by one.
&gt; db.analytics.find()
{
"_id" : ObjectId("4b253b067525f35f94b60a31"), "url" : "www.example.com",
"pageviews" : 53
}</pre>
Perl and PHP programmers are probably thinking that any character would have been a better choice than $. Both of these languages use $ as a variable prefix and will replace $-prefixed strings with their variable value in double-quoted strings. However, <a href="https://tekslate.com/modify-and-find-mongodb/">MongoDB</a> started out as a JavaScript database, and $ is a special character that isn&rsquo;t interpreted differently in JavaScript, so it was used. It is an annoying historical relic from <a href="https://tekslate.com/tutorials/mongodb-tutorials" target="_blank" rel="noopener">MongoDB&rsquo;s primordial </a>soup.
There are several options for Perl and PHP programmers. First, you could just escape the $: "\$foo". You can use single quotes, which don&rsquo;t do variable interpolation: '$foo'. Finally, both drivers allow you to de-fine your own character that will be used instead of $. In Perl, set $MongoDB::BSON::char, and in PHP set mongo.cmd_char in php.ini to =, :, ?, or any other character that you would like to use instead of $. Then, if you choose, say, ~, you would use ~inc instead of \$inc and ~gt instead of \$gt.
Good choices for the special character are characters that will not naturally appear in key names (don&rsquo;t use _ or x) and are not characters that have to be escaped themselves, which will gain you nothing and be con-fusing (such as \ or, in Perl, @).
Getting started with the "$set" modifier
"$set" sets the value of a key. If the key does not yet exist, it will be created. This can be handy for updating schema or adding user-defined keys. For example, suppose you have a simple user profile stored as a document that looks something like the following:
<pre style="text-align: justify;">&gt; db.users.findOne()
{
"_id" : ObjectId("4b253b067525f35f94b60a31"), "name" : "joe",
"age" : 30, "sex" : "male",
"location" : "Wisconsin"
}</pre>
This is a pretty bare-bones user profile. If the user wanted to store his favorite book in his profile, he could add it using "$set":
<pre style="text-align: justify;">&gt; db.users.update({"_id" : ObjectId("4b253b067525f35f94b60a31")},
... {"$set" : {"favorite book" : "war and peace"}})
Now the document will have a &ldquo;favorite book&rdquo; key:
&gt; db.users.findOne()
{
"_id" : ObjectId("4b253b067525f35f94b60a31"), "name" :</pre>
When using modifiers, the value of "_id" cannot be changed. (Note that "_id" can be changed by using whole-document replacement.) Values for any other key, including other uniquely indexed keys, can be modified.
<pre style="text-align: justify;">"joe",
"age" : 30, "sex" : "male",
"location" : "Wisconsin", "favorite book" : "war and peace"
}</pre>
If the user decides that he actually enjoys a different book, "$set" can be used again to change the value:
<pre style="text-align: justify;">&gt; db.users.update({"name" : "joe"},
... {"$set" : {"favorite book" : "green eggs and ham"}})</pre>
"$set" can even change the type of the key it modifies. For instance, if our fickle user decides that he actually likes quite a few books, he can change the value of the &ldquo;favorite book&rdquo; key into an array:
If the user realizes that he actually doesn&rsquo;t like reading, he can remove the key altogether with "$unset":
Now the document will be the same as it was at the beginning of this example.
<pre style="text-align: justify;">&gt; db.users.update({"name" : "joe"},
... {"$unset" : {"favorite book" : 1}})</pre>
Now the document will be the same as it was at the beginning of this example.
<pre style="text-align: center;">Interested in mastering <a href="https://tekslate.com/mongodb-training/" target="_blank" rel="noopener">Mongo DB Training</a>?
Learn more about Mongo DB Tutorial in this blog post.</pre>
You can also use "$set" to reach in and change embedded documents:
<pre style="text-align: justify;">&gt;db.blog.posts.findOne()
{
"_id" : ObjectId("4b253b067525f35f94b60a31"), "title" : "A Blog Post",
"content" : "...", "author" : {
"name" : "joe",
"email" : "joe@example.com"
}
}
&gt;db.blog.posts.update({"author.name" : "joe"}, {"$set" : {"author.name" : "joe schmoe"}})
&gt;db.blog.posts.findOne()
{
"_id" : ObjectId("4b253b067525f35f94b60a31"), "title" : "A Blog Post",
"content" : "...", "author" : {
"name" : "joe schmoe", "email" : "joe@example.com"
}
}</pre>
You must always use a $ <a href="https://tekslate.com/mongodb-limit/">modifier</a> for adding, changing, or removing keys. A common error people often make when starting out is to try to set the value of "foo" to "bar" by doing an update that looks like this:
<pre style="text-align: justify;">&gt; db.coll.update(criteria, {"foo" : "bar"})</pre>
This will not function as intended. It actually does a full-document replacement, re-placing the matched document with {"foo" : "bar"}. Always use $ operators for modifying individual key/value pairs.

How to Update document in MongoDB | TekSlate MongoDB Tutorials

How to Update document in MongoDB

update-document-mongodb

<h2 style="text-align: justify;">Remove Documents</h2>
In <a href="https://tekslate.com/mongodb-training/">MongoDB</a>, the&nbsp;db.collection.remove()&nbsp;method removes documents from a collection. You can remove all documents from a collection, remove all documents that match a condition, or limit the operation to remove just a single document.
This tutorial provides examples of remove operations using the&nbsp;db.collection.remove()&nbsp;method in the&nbsp;<tt class="xref mongodb mongodb-program docutils literal">mongo</tt> shell.
<h2 style="text-align: justify;">Remove All Documents</h2>
To remove all documents from a collection, pass an empty query document <tt class="docutils literal">{}</tt> to the remove()&nbsp;method. The remove()&nbsp;method does not remove the indexes.
The following example removes all documents from the <tt class="docutils literal">inventory</tt> collection:
<img class="alignnone size-full wp-image-17847" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2016/05/Screenshot_4410.png" alt="Screenshot_44" width="737" height="78" />
<h2 style="text-align: justify;">Remove Documents that Match a Condition</h2>
To remove the documents that match a deletion criteria, call the remove()method with the <tt class="docutils literal">&lt;query&gt;</tt>parameter.
<pre style="text-align: center;">Aspired to become an <a href="https://tekslate.com/mongodb-training/" target="_blank" rel="noopener">Mongo DB Training</a>?
Explore the post to discover the know-hows on Mongo DB.</pre>
The following example removes all documents from the <tt class="docutils literal">inventory</tt> collection where the <tt class="docutils literal">type</tt> field equals<tt class="docutils literal">food</tt>:
<img class="alignnone size-full wp-image-17848" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2016/05/Screenshot_4510.png" alt="Screenshot_45" width="724" height="71" />
For large deletion operations, it may be more efficient to copy the documents that you want to keep to a new collection and then use drop()on the original collection.
<h2 style="text-align: justify;">Remove a Single Document that Matches a Condition</h2>
To remove a single document, call the remove()&nbsp;method with the <tt class="docutils literal">justOne</tt> parameter set to <tt class="docutils literal">true</tt> or <tt class="docutils literal">1</tt>.
The following example removes one document from the <tt class="docutils literal">inventory</tt> collection where the <tt class="docutils literal">type</tt> field equals<tt class="docutils literal">food</tt>:
<img class="alignnone size-full wp-image-17849" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2016/05/Screenshot_4710.png" alt="Screenshot_47" width="724" height="69" />
To delete a single document sorted by some specified order, use the find and modify&nbsp;method.
For indepth understanding click on
<ul>
<li class="title"><a class="current-page" href="https://tekslate.com/mongodb-tutorials">MongoDB Tutorials</a></li>
<li class="title"><a class="current-page" href="https://tekslate.com/installation-of-mongodb/">How to install MongoDB</a></li>
<li class="title"><a href="https://tekslate.com/using-select-mongodb/" target="_blank" rel="noopener">Using Select in MongoDB</a></li>
<li class="title"><a href="https://tekslate.com/collections-in-mongodb/" target="_blank" rel="noopener">Collections in MongoDB</a></li>
<li class="title"><a href="https://tekslate.com/mongodb-index/" target="_blank" rel="noopener">MongoDB Index</a></li>
</ul>

How to delete document in MongoDB by MongoDB Experts

How to delete document in MongoDB

delete-document-mongodb

<h2>How to install MongoDB</h2>
In this tutorial, we will show you how to install <a href="https://tekslate.com/mongodb-training/">MongoDB</a> on Windows. MongoDB 2.2.3 Windows 7 Note:&nbsp;The MongoDB does not require installation, just download and extracts the zip file, configure the data directory and start it with command &ldquo;<code>mongod</code>&ldquo;.
<h2>1. Download MongoDB</h2>
Download MongoDB from official MongoDB website. Choose Windows 32 bits or 64 bits. Unzip, extracts to your prefer location, for example : <code>d:\mongodb\</code>.
<h2>2. Review MongoDB folder</h2>
In MongoDB, it contains only 10+ executable files (exe) in the bin folder. This is true, and that are the required files to MongoDB, it&rsquo;s really hard to believe for a developer like me who come from a relation database background. Figure : Files under $MongoDB/bin folder
<img class="alignnone size-full wp-image-17766" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2016/05/Screenshot_294.png" alt="Screenshot_2" width="622" height="296" />
Note:It&rsquo;s recommended to add <code>$MongoDB/bin</code> to Windows environment variable, so that you can access the MongoDB&rsquo;s commands in command prompt easily.
<h2>3. Configuration File</h2>
Create a MongoDB config file, it&rsquo;s just a text file, for example : <code>d:\mongodb\mongo.config</code>
<img class="alignnone size-full wp-image-17767" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2016/05/Screenshot_326.png" alt="Screenshot_3" width="325" height="222" />
Note:&nbsp;MongoDB need a folder (data directory) to store its data. By default, it will store in &ldquo;<code>C:\data\db</code>&ldquo;, create this folder manually. MongoDB won&rsquo;t create it for you. You can also specify an alternate data directory with <code>--dbpath</code> option.
<pre style="text-align: center;">Aspired to become an MongoDB?
Explore the post to discover the know-hows on <a href="https://tekslate.com/mongodb-training/" target="_blank" rel="noopener">MongoDB</a>.</pre>
<h2>4. Run MongoDB server</h2>
Use <code>mongod.exe --config d:\mongodb\mongo.config</code> to start MongoDB server.
<img class="alignnone size-full wp-image-17768" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2016/05/Screenshot_4100.png" alt="Screenshot_4" width="463" height="65" />
<h2>5. Connect to MongoDB</h2>
Uses <code>mongo.exe</code> to connect to the started MongoDB server.
<img class="alignnone size-full wp-image-17769" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2016/05/Screenshot_513.png" alt="Screenshot_5" width="559" height="106" />
<h2>6. MongoDB as Windows Service</h2>
Add MongoDB as Windows Service, so that MongoDB will start automatically following each system restart. Install as Windows Service with <code>--install</code>. <img class="alignnone size-full wp-image-17770" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2016/05/Screenshot_610.png" alt="Screenshot_6" width="641" height="50" />
A Windows service named &ldquo;MongoDB&rdquo; is created. <img class="alignnone size-full wp-image-17771" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2016/05/Screenshot_710.png" alt="Screenshot_7" width="632" height="293" /> <img class="alignnone size-full wp-image-17772" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2016/05/Screenshot_810.png" alt="Screenshot_8" width="868" height="291" />
<h2>7. FAQs</h2>
1. Install MongoDB as Windows service on Windows 8, but hit &ldquo;Access is denied.&rdquo; error message : <img class="alignnone size-full wp-image-17773" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2016/05/Screenshot_95.png" alt="Screenshot_9" width="871" height="152" />
To fix it, run the Command Prompt with Administrative Privileges &ndash; right click on the command prompt icon, select run as administrator.
<h2>Other Interesting Reads</h2>
<ul>
<li class="title"><a class="current-page" href="https://tekslate.com/mongodb-tutorials">MongoDB Tutorials</a></li>
<li class="title"><a class="current-page" href="https://tekslate.com/installation-of-mongodb/">How to install MongoDB</a></li>
<li class="title"><a href="https://tekslate.com/using-select-mongodb/" target="_blank" rel="noopener">Using Select in MongoDB</a></li>
<li class="title"><a href="https://tekslate.com/collections-in-mongodb/" target="_blank" rel="noopener">Collections in MongoDB</a></li>
<li class="title"><a href="https://tekslate.com/mongodb-index/" target="_blank" rel="noopener">MongoDB Index</a></li>
<li class="title"><a href="https://tekslate.com/mongodb-data-types" target="_blank" rel="noopener">MongoDB Data Types</a></li>
</ul>

How to Install MongoDB ? By MongoDB Experts - TekSlate

How to install MongoDB

installation-of-mongodb

&nbsp;
<h2 style="text-align: justify;">&nbsp;MongoDB supports many datatypes</h2>
Types of <a href="https://tekslate.com/mongodb-training/">MongoDB</a> datatypes
-String : This is most commonly used <a href="mongodb-data-types" target="_blank" rel="noopener">datatype</a> to store the data. String in mongodb must be UTF-8 valid.
-Integer : This type is used to store a numerical value. Integer can be 32 bit or 64 bit depending upon your server.
-Boolean : This type is used to store a boolean (true/ false) value.
-Double : This type is used to store floating-point values.
-Min/ Max keys : This type is used to compare a value against the lowest and highest BSON elements.
-Arrays : This type is used to store arrays or lists or multiple values into one key.
-Timestamp : timestamp. This can be handy for recording when a document has been modified or added.
-Object : This data type is used for embedded documents.
<div class="highlight">
<pre style="text-align: center;">These core tutorials will help you to learn the fundamentals of Mongo DB.For an in-depth understanding and practical experience, explore <a href="https://tekslate.com/mongodb-training/" target="_blank" rel="noopener">Online Mongo DB Training</a>.</pre>
</div>
<div class="highlight">&nbsp;</div>
-Null : This type is used to store a Null value.
-Symbol : This datatype is used identically to a string however, it's generally reserved for languages that use a specific symbol type.
-Date : This datatype is used to store the current date or time in <a href="unix-commands-2" target="_blank" rel="noopener">UNIX</a> time format. You can specify your own date time by creating object of Date and passing day, month, year into it.
-Object ID : This datatype is used to store the document&rsquo;s ID.
-Binary data : This datatype is used to store binary data.
-Code : This datatype is used to store <a href="javascript-tutorials" target="_blank" rel="noopener">javascript</a> code into the document.
-Regular expression : This datatype is used to store regular expression.
For indepth understanding click on
<ul>
<li class="title"><a class="current-page" href="https://tekslate.com/mongodb-tutorials">MongoDB Tutorials</a></li>
<li class="title"><a class="current-page" href="https://tekslate.com/installation-of-mongodb/">How to install MongoDB</a></li>
<li class="title"><a href="https://tekslate.com/using-select-mongodb/" target="_blank" rel="noopener">Using Select in MongoDB</a></li>
<li class="title"><a href="https://tekslate.com/collections-in-mongodb/" target="_blank" rel="noopener">Collections in MongoDB</a></li>
<li class="title"><a href="https://tekslate.com/mongodb-index/" target="_blank" rel="noopener">MongoDB Index</a></li>
</ul>

MongoDB Data Types | TekSlate MongoDB Tutorials

MongoDB Data Types

mongodb-data-types

<a href="https://tekslate.com/mongodb-training/">MongoDB </a>is an open-source document-oriented database. Document-oriented means it stores the data in a file. <a href="mongodb-tutorials" target="_blank" rel="noopener">MongoDB</a> comes under the category of NoSql database. It stores the data in BSON (Binary JSON) format. It can be accessed through javascript notation and comes with their own shell.
Database &ndash; It is a set of collections.
If you do a little research to find out how to create a database in MongoDB, you&rsquo;ll find documentation for the function &ldquo;db.createCollection()&rdquo;. This is actually how you create a database, but it&rsquo;s referred to as a collection in NoSQL.
To create a MongoDB database:
-&ldquo;Use&rdquo; the database.
-Create a collection in the<a href="mongodb-database" target="_blank" rel="noopener"> database.</a>
-Verify that you got what you wanted.
<pre style="text-align: center;">Learn MongoDB by Tekslate - Fastest growing sector in the industry.Explore Online <a href="https://tekslate.com/mongodb-training/" target="_blank" rel="noopener">MongoDB Training</a> and course is aligned with industry needs &amp; developed by industry veterans.Tekslate will turn you into MongoDB Expert.</pre>
Assume you have installed <a href="mongodb-tutorials" target="_blank" rel="noopener">MongoDB</a> successfully in your system. Go to the terminal (ctrl + Alt + T) and type mongo and press enter. It opens up a mongo shell.
xyz@xyz-300E4c-300E5c-300E7c:$ mongo <a href="mongodb-index" target="_blank" rel="noopener">MongoDB</a> shell version: 2.4.6 Connecting to: test &gt;
To check all the database
<div id="crayon-57394a246496a043772390" class="crayon-syntax crayon-theme-classic crayon-font-monaco crayon-os-pc print-yes notranslate" style="text-align: justify;" data-settings=" minimize scroll-mouseover">
<table class="crayon-table">
<tbody>
<tr class="crayon-row">
<td class="crayon-nums " data-settings="show">
<div class="crayon-nums-content">
<div class="crayon-num" data-line="crayon-57394a246496a043772390-1">1</div>
</div>
</td>
<td class="crayon-code">
<div class="crayon-pre">
<div id="crayon-57394a246496a043772390-1" class="crayon-line"># show dbs</div>
</div>
</td>
</tr>
</tbody>
</table>
Let&rsquo;s insert some records in our emp collection. We have not created any database yet but MongoDB creates when the record is inserted.
<pre style="padding-left: 30px;">dp.emp.insert({
firstname: 'Raj",
lastname: 'kumar'
 dob: '09/07/1989',
 designation:'SE';
 nationality:'India',
 gender 'M'
 });
 dp.emp.insert({
 firstname: 'Robin',
 lastname: 'yadav',
 dob: '10/08/1987',
 designation:'Manager',
 nationality:'India',
 gender 'M'
 });
 dp.emp.insert({
 firstname: 'Tang',
 lastname: 'sharma',
 dob: '12/01/1986',
 designation:'TL',
 nationality:'India',
 gender 'M'
 });
 dp.emp.insert({
 firstname: 'parul',
 lastname: 'iti',
 dob: '13/08/1983',
 designation:'Emp',
 nationality:'India',
 gender 'F'
 });</pre>
The value is inserted successfully, you can check through find() command.
<div class="crayon-main" style="padding-left: 30px;"><img class="alignnone size-full wp-image-18814" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2016/05/Capture.319.png" alt="Capture.319" width="698" height="106" /></div>
<div class="crayon-main">_id field is created by MongoDB automatically. It is the auto-increment field.</div>
<div class="crayon-main">&nbsp;</div>
</div>
<div class="crayon-main" style="text-align: justify;">To view the output in a proper format.</div>
<div class="crayon-main" style="text-align: justify;">&nbsp;</div>
<div class="crayon-main" style="text-align: justify;">db.emp.find().forEach(printjson);</div>
<div class="crayon-main" style="text-align: justify;">
For indepth understanding click on
<ul>
<li class="title"><a class="current-page" href="https://tekslate.com/mongodb-tutorials">MongoDB Tutorials</a></li>
<li class="title"><a class="current-page" href="https://tekslate.com/installation-of-mongodb/">How to install MongoDB</a></li>
<li class="title"><a href="https://tekslate.com/using-select-mongodb/" target="_blank" rel="noopener">Using Select in MongoDB</a></li>
<li class="title"><a href="https://tekslate.com/collections-in-mongodb/" target="_blank" rel="noopener">Collections in MongoDB</a></li>
<li class="title"><a href="https://tekslate.com/mongodb-index/" target="_blank" rel="noopener">MongoDB Index</a></li>
</ul>
</div>

MongoDB Database | TekSlate MongoDB Tutorials

MongoDB Database

mongodb-database

The documents stored in MongoDB are JSON-like. All data stored into the collection are in BSON format.
<h2>Switch to a MongoDB database</h2>
<pre class="well"> &gt; use myinfo
switch to db myinfo</pre>
<h2>Define a document for MongoDB database</h2>
<pre class="well"> &gt; document=({"user_id" : "ABCDBWN","password" :"ABCDBWN" ,"date_of_join" : "15/10/2010" ,"education" :"B.C.A." , "profession" : "DEVELOPER","interest" : "MUSIC","community_name" :["MODERN MUSIC", "CLASSICAL MUSIC","WESTERN MUSIC"],"community_moder_id" : ["MR. BBB","MR. JJJ","MR MMM"],"community_members" : [500,200,1500],"friends_id" : ["MMM123","NNN123","OOO123"],"ban_friends_id" :["BAN123","BAN456","BAN789"]});

</pre>
<h2>Defined document shows in command prompt</h2>
<pre class="well">{
 "user_id" : "ABCDBWN",
 "password" : "ABCDBWN",
 "date_of_join" : "15/10/2010",
 "education" : "B.C.A.",
 "profession" : "DEVELOPER",
 "interest" : "MUSIC",
 "community_name" : [
 "MODERN MUSIC",
 "CLASSICAL MUSIC",
 "WESTERN MUSIC"
 ],
 "community_moder_id" : [
 "MR. BBB",
 "MR. JJJ",
 "MR MMM"
 ],
 "community_members" : [
 500,
 200,
 1500
 ],
 "friends_id" : [
 "MMM123",
 "NNN123",
 "OOO123"
 ],
 "ban_friends_id" : [
 "BAN123",
 "BAN456",
 "BAN789"
 ]
}

</pre>
<h2>Insert a document into a collection</h2>
To save the above document into the collection "userdetails" under "myinfo" database the following command can be used -
<pre class="well">&gt; db.userdetails.insert(document)</pre>
<h2>Write document using linebreak</h2>
Linebreaks can also be used while typing a document. This can be useful when writing a lengthy document as shown bellow:
<pre class="well" style="padding-left: 30px;">&gt;document=({"user_id" : "ABCDBWN","password" :"ABCDBWN" ,"date_of_join" : "15/10/2010" ,
"education" :"B.C.A." , "profession" : "DEVELOPER","interest" : "MUSIC",
"community_name" :["MODERN MUSIC", "CLASSICAL MUSIC","WESTERN MUSIC"],
"community_moder_id" : ["MR. BBB","MR. JJJ","MR MMM"],
"community_members" : [500,200,1500],"friends_id" : ["MMM123","NNN123","OOO123"],
"ban_friends_id" :["BAN123","BAN456","BAN789"]});

</pre>
<h2>Insert data into a collection without defining a document</h2>
Data can be insert directly through the shell without defining the document -
<pre class="well" style="padding-left: 30px;">&gt;db.userdetails.insert({"user_id" : "xyz123","password" :"xyz123" ,"date_of_join" : "15/08/2010" ,
"education" :"M.C.A." , "profession" : "Software consultant","interest" : "Film",
"community" : [
{
"name" : "DDD FILM CLUB",
"moder_id" : "MR. DBNA",
"members" : "25000",
},
{
"name" : "AXN MOVIES",
"moder_id" : "DOGLUS HUNT",
"members" : "15000",
},
{
"name" : "UROPEAN FILM LOVERS",
"moder_id" : "AMANT LUIS",
"members" : "20000",
}
],
"friends" :[
{
"user_id" : "KKK258",
},
{
"user_id" : "LLL147",
},
{
"user_id" : "MMM369", 	 
}
],
"ban_friends" :[
{
"user_id" : "BAN147" 	 
}, 	 
{
"user_id" : "BAN258"
},
{
"user_id" : "BAN369"
}
] 	 
});

</pre>
<pre style="text-align: center;">Inclined to build a profession as Mongo DB&nbsp;Developer?
Then here is the blog post on <a href="https://tekslate.com/mongodb-training/" target="_blank" rel="noopener">Mongo DB&nbsp;Training</a>.</pre>
<h2>View the inserted data into the collection</h2>
<pre class="well">&gt;db.userdetails.find();</pre>
<pre class="well">{
 "user_id" : "xyz123",
 "password" : "xyz123",
 "date_of_join" : "15/08/2010",
 "education" : "M.C.A.",
 "profession" : "Software consultant",
 "interest" : "Film",
 "community" : [
 {
 "name" : "DDD FILM CLUB",
 "moder_id" : "MR. DBNA",
 "members" : "25000"
 },
 {
 "name" : "AXN MOVIES",
 "moder_id" : "DOGLUS HUNT",
 "members" : "15000"
 },
 {
 "name" : "UROPEAN FILM LOVERS",
 "moder_id" : "AMANT LUIS",
 "members" : "20000"
 }
 ],
 "friends" : [
 {
 "user_id" : "KKK258"
 },
 {
 "user_id" : "LLL147"
 },
 {
 "user_id" : "MMM369"
 }
 ],
 "ban_friends" : [
 {
 "user_id" : "BAN147"
 },
 {
 "user_id" : "BAN258"
 },
 {
 "user_id" : "BAN369"
 }
 ]
}

</pre>

How to insert document in MongoDB

insert-document-mongodb

Indexes can support the efficient execution of queries. Without indexes, MongoDB must perform a collection scan, i.e. scan every document in a collection, to select those documents that match the query statement. If an appropriate index exists for a query, MongoDB can use the index to limit the number of documents it must inspect. Use the create index() method to create an index on a collection. Indexes can support the efficient execution of queries. MongoDB automatically creates an index on the <tt class="docutils literal">_id</tt> field upon the creation of a collection. To create an index on a field or fields, pass to the create index()method an index key specification document that lists the fields to index and the index type for each field:
<h2>MongoDB Index Types</h2>
MongoDB provides different types of indexes to support specific types of data and queries.
<h3>Default&nbsp;_id</h3>
All the collections of MongoDB have an index on the&nbsp;_id&nbsp;field that exists by default. If no <a class="zem_slink" title="Value (personal and cultural)" href="http://en.wikipedia.org/wiki/Value_%28personal_and_cultural%29" target="_blank" rel="noopener wikipedia">values</a> specified for the _id the MongoDB will create an _id field with an ObjectId value. The _id index is unique, it restricts clients from inserting two documents with the same value for the _id field.
<h3>Single Field</h3>
<a href="mongodb-database" target="_blank" rel="noopener">MongoDB</a> supports user-defined indexes on a&nbsp;<a class="zem_slink" title="Single-field dictionary" href="http://en.wikipedia.org/wiki/Single-field_dictionary" target="_blank" rel="noopener wikipedia">single field</a> of a document. Here is the example below considering a single-column index.
<pre class="well">db.userdetails.find().sort({"education":1})</pre>
The above example shows the "education" column from the collection of user details is sorting in ascending order.
<h3>Compound Index</h3>
MongoDB also supports user-defined indexes in multiple fields. The order of fields listed in a compound index has significance. For instance, if a compound index consists of {"education": 1, "password": -1 }, the index sorts first by education and then, within each education value, sort by a password. Consider the following illustration of this compound index:
<pre class="well">db.userdetails.find().sort({"education":1,"password":-1})</pre>
<h3>Multikey Index</h3>
<a href="https://tekslate.com/mongodb-tutorials">MongoDB</a> uses multikey indexes to index the content stored in arrays. When you index on a column that holds an array value, MongoDB creates separate index entries for every element of the array. These multikey indexes allow queries to select documents that contain arrays by matching on element or elements of the arrays. Here is a sample document within a collection:
<pre class="well">{
 "_id" : ObjectId("528f34950fe5e6467e58ae77"),
 "user_id" : "user1",
 "password" : "1a2b3c",
 "sex" : "Male",
 "age" : 17,
 "date_of_join" : "16/10/2010",
 "education" : "M.C.A.",
 "profession" : "CONSULTANT",
 "interest" : "MUSIC",
 "extra" : {
 "friends" : {
 "valued_friends_id" : [
 "kumar",
 "harry",
 "anand"
 ],
 "ban_friends_id" : [
 "Amir",
 "Raja",
 "mont"
 ]
 }
 }
}

Consider the following illustration of a multikey index:</pre>
<pre class="well">db.userdetails.find().sort({"extra.friends.ban_friends_id":1})

</pre>
Here in the above example, the 'extra' is an array, and 'friends' and 'ban_firends_id' are subarrays.
<h3>Geospatial Index</h3>
To support efficient queries of geospatial coordinate data, MongoDB provides two special indexes:&nbsp;2d indexes&nbsp;and 2sphere indexes uses for planar geometry when returning results spherical geometry to return results.
<h3>Text Indexes</h3>
Another type of index that MongoDB provides is text index, which supports searching for string content in a collection. These text indexes do not store language-specific stop words (e.g. &ldquo;the&rdquo;, &ldquo;a&rdquo;, &ldquo;or&rdquo;) and restrict the words in a collection to only store root words.
<h3>Hashed Indexes</h3>
To support hash-based sharding, MongoDB provides a hashed index type, which indexes the hash of the value of a field. These indexes have a more random distribution of values along with their range, but only support equality matches and cannot support range-based queries.
<h2>Index Properties</h2>
<h3>Unique Indexes</h3>
The unique property for an index causes rejects duplicate values for the indexed field. To create a unique index on a field that already has duplicate values. Other than the unique constraint, unique indexes are functionally interchangeable with other MongoDB indexes.
<h3>Sparse Indexes</h3>
The sparse property of an index ensures that the index only contains entries for documents that have the indexed field and skips documents that do not have the indexed field. The <a class="zem_slink" title="Database index" href="http://en.wikipedia.org/wiki/Database_index" target="_blank" rel="noopener wikipedia">sparse index</a> option can be combined with the unique index option to reject documents that have duplicate values for a field but ignore that do not have the indexed key.
<h3>TTL Indexes</h3>
Another special index is TTL indexes that can be used to automatically remove documents from a collection after a certain amount of time. This is ideal for certain types of information like machine generated event data, logs, and session information that only need to stay behind in a database for a finite amount of time.
<h2>MongoDB&nbsp;Single Field Indexes</h2>
All the indexes in MongoDB are B-tree indexes, which supports equality matches and range queries. Internally the index arranged items in an order, sorted by the value of the index field. The ordering of the index allows MongoDB to return sorted results using the order of documents in the index. MongoDB provides indexes on any field in a collection of documents. MongoDB supports either a single field or multiple fields depending on the operations a user needs. The default index for collections have MongoDB on the _id field, the additional indexes can be added by the user to support important queries and operations. Here is the documents in the collection 'empinfo'.
<pre class="well">{
 "_id" : ObjectId("548eb3a051ca033c1c01054d"),
 "emp_id" : "SALS",
 "emp_name" : "Pat",
 "designation" : "clerk",
 "department" : "sales"
}
{
 "_id" : ObjectId("548eb3a051ca033c1c01054e"),
 "emp_id" : "OFFC",
 "emp_name" : "Jons",
 "designation" : "peon",
 "department" : "sales"
}
{
 "_id" : ObjectId("548eb3a051ca033c1c01054f"),
 "emp_id" : "CLC",
 "emp_name" : "Tnit",
 "designation" : "president",
 "department" : "sales"
}
The following command create the index on emp_id column.

</pre>
<pre class="well">&gt; db.empinfo.ensureIndex( { "emp_id" : 1 } );
{
 "createdCollectionAutomatically" : true,
 "numIndexesBefore" : 1,
 "numIndexesAfter" : 2,
 "ok" : 1
}

If you want to see the list of created index, here is the following command.

&gt; db.system.indexes.find();
{ "v" : 1, "key" : { "_id" : 1 }, "name" : "_id_", "ns" : "empinfo.empinfo" }
{ "v" : 1, "key" : { "emp_id" : 1 }, "name" : "emp_id_1", "ns" : "empinfo.empinfo" }</pre>
<h3>Indexes on Embedded Fields</h3>
The indexes can be created on fields embedded in sub-documents, as you can index top-level fields in documents. There is a difference between Indexes on embedded fields and indexes on sub-documents. The indexes on subdocument include the full content up to the maximum index size where as indexes on embedded fields allow the user to use a &ldquo;dot notation,&rdquo; to self-searching into sub-documents.
<pre style="text-align: center;">Aspired to become an Mongo DB? Explore the post to discover the know-hows on <a href="https://tekslate.com/mongodb-training/" target="_blank" rel="noopener">Mongo DB Training</a>.</pre>
Consider the following collection named 'empinfo' that contains the documents.
<pre class="well">{
 "_id" : ObjectId("548fe6d898fd7de25e8d3aa9"),
 "emp_id" : "SALS",
 "emp_name" : "Pat",
 "address" : [
 {
 "street" : "Court Street",
 "city" : "London",
 "zip" : "5698722"
 }
 ]
}
{
 "_id" : ObjectId("548fe6d898fd7de25e8d3aaa"),
 "emp_id" : "OFFC",
 "emp_name" : "Jones",
 "address" : [
 {
 "street" : "Church Avenue",
 "city" : "Paris",
 "zip" : "632902"
 }
 ]
}

The following command create the index on address.zip &nbsp;field, using the following specification:</pre>
<pre class="well">&gt; db.empinfo.ensureIndex( { "address.zip": 1 } );
{
 "createdCollectionAutomatically" : true,
 "numIndexesBefore" : 1,
 "numIndexesAfter" : 2,
 "ok" : 1
}

If you want to see the created index, see the following command.


&gt; db.system.indexes.find();
{ "v" : 1, "key" : { "_id" : 1 }, "name" : "_id_", "ns" : "empinfo.empinfo" }
{ "v" : 1, "key" : { "address.zip" : 1 }, "name" : "address.zip_1", "ns" : "empinfo.empinfo" }
&gt;

</pre>
<h3>Indexes on Subdocuments</h3>
An index can also be created in the subdocument. Here in the below, a sample collection named 'empinfo' contain a field address within its documents.
<pre class="well">{
 "_id" : ObjectId("54901b4b4b71cc67737765a5"),
 "emp_id" : "SALS",
 "emp_name" : "Pat",
 "address" : {
 "street" : "Court Street",
 "city" : "London",
 "zip" : "5698722"
 }
}
{
 "_id" : ObjectId("54901b4b4b71cc67737765a6"),
 "emp_id" : "MARK",
 "emp_name" : "James",
 "address" : {
 "street" : "Church Avenue",
 "city" : "Paris",
 "zip" : "532460"
 }
}


The&nbsp;address&nbsp;field is a subdocument, containing the embedded fields&nbsp;city&nbsp;and&nbsp;zip. The following command creates an index on the&nbsp;address &nbsp;field as a whole.</pre>
<pre class="well">&gt; db.empinfo.ensureIndex( { address: 1 } );
{
 "createdCollectionAutomatically" : false,
 "numIndexesBefore" : 1,
 "numIndexesAfter" : 2,
 "ok" : 1
}

If you want to lists the creating index, here is the command below.

&gt; db.system.indexes.find();
{ "v" : 1, "key" : { "_id" : 1 }, "name" : "_id_", "ns" : "empinfo.empinfo" }
{ "v" : 1, "key" : { "address" : 1 }, "name" : "address_1", "ns" : "empinfo.empinfo" }

The following query can use the index on the&nbsp;address &nbsp;field :</pre>
<pre class="well">&gt; db.empinfo.find( { address: { street: "Court Street", city: "London",zip:"5698722" } } ).pretty();

{
 "_id" : ObjectId("54901b4b4b71cc67737765a5"),
 "emp_id" : "SALS",
 "emp_name" : "Pat",
 "address" : {
 "street" : "Court Street",
 "city" : "London",
 "zip" : "5698722"
 }
}

</pre>
From the above output it seems that, when performing equality matches on subdocuments, field order matters and the subdocuments must match exactly. See the example below, the following query does not match the above document:
<pre class="well">db.empinfo.find( { address: { city: "London",zip:"5698722",street: "Court Street" } } );

</pre>
For indepth understanding click on
<ul>
<li class="title"><a class="current-page" href="https://tekslate.com/installation-of-mongodb/">How to install MongoDB</a></li>
<li class="title"><a href="https://tekslate.com/using-select-mongodb/" target="_blank" rel="noopener">Using Select in MongoDB</a></li>
<li class="title"><a href="https://tekslate.com/collections-in-mongodb/" target="_blank" rel="noopener">Collections in MongoDB</a></li>
<li class="title"><a href="https://tekslate.com/mongodb-index/" target="_blank" rel="noopener">MongoDB Index</a></li>
</ul>

Explain Mongo DB

MongoDB Index

mongodb-index

<h2 style="text-align: justify;">Remove Collection in MongoDB</h2>
We have already learned how to insert records into a collection and also learned how to update the <a class="zem_slink" title="Document" href="http://en.wikipedia.org/wiki/Document" target="_blank" rel="noopener wikipedia">document</a> within a collection based on certain criteria. In this page, we are going to discuss how to remove document and entire collection.
remove() is used to remove a document and a collection. It may be a good practice if you execute a find() before removing a document as you can can fix a criteria for removing the document.
Our <a class="zem_slink" title="Database" href="http://en.wikipedia.org/wiki/Database" target="_blank" rel="noopener wikipedia">database</a> name is 'myinfo' and our collection name is 'userdetails'. Here, inserting one more record.
<pre class="well">&gt; document=({"user_id" : "testuser","password" :"testpassword" ,"date_of_join" : "16/10/2010" ,"education" :"M.C.A." , "<a class="zem_slink" title="Profession" href="http://en.wikipedia.org/wiki/Profession" target="_blank" rel="noopener wikipedia">profession</a>" : "CONSULTANT","interest" : "MUSIC","community_name" :["MODERN MUSIC", "CLASSICAL MUSIC","WESTERN MUSIC"],"community_moder_id" : ["MR. BBB","MR. JJJ","MR MMM"],"community_members" : [500,200,1500],"friends_id" : ["MMM123","NNN123","OOO123"],"ban_friends_id" :["BAN123","BAN456","BAN789"]});</pre>
<pre class="well">&gt; db.userdetails.insert(document) 

</pre>
<h2 style="text-align: justify;">View the inserted data into the collection</h2>
<pre class="well">&gt;db.userdetails.find().pretty();

N.B. find() method displays the documents in a non structured format but to display the results in a formatted way, the pretty() method can be used.</pre>
<pre class="well">{
 "user_id" : "MNOPBWN",
 "password" : "MNOPBWN",
 "date_of_join" : "16/10/2010",
 "education" : "M.C.A.",
 "profession" : "CONSULTANT",
 "interest" : "MUSIC",
 "community_name" : [
 "MODERN MUSIC",
 "CLASSICAL MUSIC",
 "WESTERN MUSIC"
 ],
 "community_moder_id" : [
 "MR. BBB",
 "MR. JJJ",
 "MR MMM"
 ],
 "community_members" : [
 500,
 200,
 1500
 ],
 "friends_id" : [
 "MMM123",
 "NNN123",
 "OOO123"
 ],
 "ban_friends_id" : [
 "BAN123",
 "BAN456",
 "BAN789"
 ]
}
{
 "user_id" : "QRSTBWN",
 "password" : "NEWPASSWORD",
 "date_of_join" : "17/10/2010",
 "education" : "M.B.A.",
 "profession" : "MARKETING",
 "interest" : "MUSIC",
 "community_name" : [
 "MODERN MUSIC",
 "CLASSICAL MUSIC",
 "WESTERN MUSIC"
 ],
 "community_moder_id" : [
 "MR. BBB",
 "MR. JJJ",
 "MR MMM"
 ],
 "community_members" : [
 500,
 200,
 1500
 ],
 "friends_id" : [
 "MMM123",
 "NNN123",
 "OOO123"
 ],
 "ban_friends_id" : [
 "BAN123",
 "BAN456",
 "BAN789"
 ]
}
{
 "user_id" : "testuser",
 "password" : "testpassword",
 "date_of_join" : "16/10/2010",
 "education" : "M.C.A.",
 "profession" : "CONSULTANT",
 "interest" : "MUSIC",
 "community_name" : [
 "MODERN MUSIC",
 "CLASSICAL MUSIC",
 "WESTERN MUSIC"
 ],
 "community_moder_id" : [
 "MR. BBB",
 "MR. JJJ",
 "MR MMM"
 ],
 "community_members" : [
 500,
 200,
 1500
 ],
 "friends_id" : [
 "MMM123",
 "NNN123",
 "OOO123"
 ],
 "ban_friends_id" : [
 "BAN123",
 "BAN456",
 "BAN789"
 ]
}</pre>
Document written in command prompt
<div class="highlight">
<pre style="text-align: center;">These core tutorials will help you to 
learn the fundamentals of Mongo DB.
For an in-depth understanding and practical experience, 
explore <a href="https://tekslate.com/mongodb-training/" target="_blank" rel="noopener">Online Mongo DB Training</a>.</pre>
</div>
<div class="highlight">&nbsp;</div>
<h2 style="text-align: justify;">Remove document with remove()</h2>
If we want to remove the document from the collection 'userdetails' which contains the userid "testuser" the following <a href="https://tekslate.com/mongodb-tutorials">mongodb </a>command can be used :
<pre class="well">&gt;db.userdetails.remove( { "user_id" : "testuser" } )</pre>
<h2 style="text-align: justify;">Remove all data from a collection</h2>
If we want to remove all data from the collection 'userdetails' the following mongodb command can be used :
<pre class="well">&gt;db.userdetails.remove({}) 
</pre>
<h2 style="text-align: justify;">Remove a collection using drop()</h2>
If we want to remove the entire 'userdetails' collection, including all of its documents the following mongodb command can be used :
<pre class="well">&gt;db.userdetails.drop()
</pre>
<h2 style="text-align: justify;">Output</h2>
<pre class="well">&gt; db.userdetails.drop();
true</pre>
The drop() returns either true or false. The above function returns true, it means that the operation has completed successfully.
<h2 style="text-align: justify;">Remove an entire Database using dropDatabase()</h2>
If we want to remove an entire database the following mongodb command can be used :
<pre class="well">&gt;db.dropDatabase()
</pre>
It should be a good habit if you use db command in mongodb prompt to know which database is currently working and you can be sure before removing the database.
<pre class="well">&gt; db
myinfo
</pre>
<pre class="well">&gt;db.dropDatabase(); 
{ "dropped" : "myinfo", "ok" : 1 }

</pre>

Delete/Remove collection in MongoDB | MongoDB Online

Delete/Remove collection in MongoDB

deleteremove-collection-mongodb

<h2>Collection</h2>
A collection may store number of documents. A collection is analogous to a table of a <a class="zem_slink" title="Relational database management system" href="http://en.wikipedia.org/wiki/Relational_database_management_system" target="_blank" rel="noopener wikipedia">RDBMS</a>. A collection may store documents those who are not same in structure. This is possible because MongoDB is a <a class="zem_slink" title="Database schema" href="http://en.wikipedia.org/wiki/Database_schema" target="_blank" rel="noopener wikipedia">Schema</a>-free <a class="zem_slink" title="Database" href="http://en.wikipedia.org/wiki/Database" target="_blank" rel="noopener wikipedia">database</a>. In a relational database like MySQL, a schema defines the organization / structure of data in database. MongoDB does not require such a set of formula defining structure of data. So, it is quite possible to store documents of varying structures in a collection. Practically, you don't need to define a column and it's <a class="zem_slink" title="Data type" href="http://en.wikipedia.org/wiki/Data_type" target="_blank" rel="noopener wikipedia">datatype</a> unlike in RDBMS, while working with MongoDB. In the following code, it is shown that two MongoDB documents, belongs to same collection, storing data of different structures. A collection is created, when the first document is inserted.
<h2 class="subheading">Valid collection names</h2>
Collection names must begin with letters or an underscore. A Collection name may contain numbers. You can't use "$" character within the name of a collection. "$" is reserved. A Collection name must not exceed 128 characters. It will be nice if you keep it within 80/90 characters. Using a "." (dot) notation, collections can be organized in named groups. For example, tutorials.php and tutorials.javascript both belong to tutorials. This mechanism is called as collection namespace which is for user primarily. Databases don't have much to do with it. Following is how to use it programmatically :
db.tutorials.php.findOne()
<div class="highlight">
<pre style="text-align: center;">These core tutorials will help you to learn the fundamentals of Mongo DB.
For an in-depth understanding and practical experience, explore <a href="https://tekslate.com/mongodb-training/" target="_blank" rel="noopener">Online Mongo DB Training</a>.</pre>
</div>
<div class="highlight">&nbsp;</div>
<h2 class="subheading">capped collections</h2>
Imagine that you want to log the activities happening with application. you want to store data in the same order it is inserted.<a href="https://tekslate.com/tutorials/mongodb-tutorials"> MongoDB</a> offers Capped collections for doing so. Capped collections are collections which can store data in the same order it is inserted. It is very fixed size, high-performance and "auto-<a class="zem_slink" title="FIFO" href="http://en.wikipedia.org/wiki/FIFO" target="_blank" rel="noopener wikipedia">FIFO</a> age-Out". That is, when the allotted space is fully utilized, newly added objects (documents) will replace the older ones in the same order it is inserted. Since data is stored in the natural order, that is the order it is inserted, while retrieving data, no ordering is required, unless you want to reverse the order. New objects can be inserted into a capped collection. Existing objects can be updated. But you can't remove an individual object from the capped collection. Using drop command, you have to remove all the documents. After drop, you have to recreate the capped collection. Presently, maximum size for a capped collection is 1e9(i.e. 1X109) for 32 bit machines. For 64 bit machines, there is no theoretical limit. Practically, it can be extended till your system resources permit. Capped collections can be used for logging, caching and auto archiving.
<h2 class="subheading">Use number of collections instead of one</h2>
This omits the requirement if creating index since you are not storing some repeating data on each object. If applied on a suitable situation, it can enhance the performance.
<h2 class="subheading">Metadata</h2>
Information about a database is stored in certain collections. They are grouped in system namespace, as
dbname.system.*
The following table shows the collections and what they store
<table class="table table-bordered">
<tbody>
<tr>
<th>Collections with namespace</th>
<th>Description</th>
</tr>
<tr>
<td>dbname.system.namespaces</td>
<td>list of all namespaces</td>
</tr>
<tr>
<td>dbname.system.indexes</td>
<td>list of all indexes</td>
</tr>
<tr>
<td>dbname.system.profile</td>
<td>stores database profiling information</td>
</tr>
<tr>
<td>dbname.system.users</td>
<td>list of users who may access the database</td>
</tr>
<tr>
<td>dbname.local.sources</td>
<td>stores replica slave configuration data and state</td>
</tr>
<tr>
<td>dbname.local.sources</td>
<td>stores replica slave configuration data and state</td>
</tr>
</tbody>
</table>
There are two more options to store metadata : database.ns files stores additional namespace / index metadata if exists. Information on the structure of a stored object is stored within the object itself.
For indepth understanding click on
<ul>
<li class="title"><a class="current-page" href="https://tekslate.com/mongodb-tutorials">MongoDB Tutorials</a></li>
<li class="title"><a class="current-page" href="https://tekslate.com/installation-of-mongodb/">How to install MongoDB</a></li>
<li class="title"><a href="https://tekslate.com/using-select-mongodb/" target="_blank" rel="noopener">Using Select in MongoDB</a></li>
<li class="title"><a href="https://tekslate.com/collections-in-mongodb/" target="_blank" rel="noopener">Collections in MongoDB</a></li>
<li class="title"><a href="https://tekslate.com/mongodb-index/" target="_blank" rel="noopener">MongoDB Index</a></li>
</ul>

Collections in MongoDB - Tekslate

Collections in MongoDB

collections-in-mongodb

<h2>REST Interfaces</h2>
<div id="eve-python" class="section">
<h3>Eve (Python)</h3>
Eve is an open-source <a href="tutorials-tableau" target="_blank" rel="noopener">Python</a> REST <a class="zem_slink" title="Application programming interface" href="http://en.wikipedia.org/wiki/Application_programming_interface" target="_blank" rel="noopener wikipedia">API</a> framework designed for human beings. It allows us to effortlessly build and deploy highly customizable, fully featured <a class="zem_slink" title="Representational state transfer" href="http://en.wikipedia.org/wiki/Representational_state_transfer" target="_blank" rel="noopener wikipedia">RESTful</a> Web Services powered by MongoDB. The codebase is thoroughly tested under Python 2.6, 2.7, 3.3, 3.4, and PyPy. All you need to bring your REST Web Service online is a <a href="mongodb-database" target="_blank" rel="noopener">MongoDB database</a>, a configuration file, and a launch script. Overall, you will find that configuring and fine-tuning your API is a very simple process.
-Emphasis on REST
-Full range of CRUD operations
-Customizable resource endpoints
-Customizable, multiple item endpoints
-Filtering and Sorting
-Pagination
-HATEOAS
-JSON and <a href="xml" target="_blank" rel="noopener">XML</a> Rendering
-Conditional Requests
-Data Integrity and Concurrency Control
-Bulk Inserts
-Data Validation
-Extensible Data Validation
-Resource-level Cache-Control
-API Versioning
-Document Versioning
-Authentication
</div>
<h3>RESTHeart (Java)</h3>
RESTHeart Java REST API server for MongoDB, built on top of Undertow non-blocking <a class="zem_slink" title="Hypertext Transfer Protocol" href="http://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol" target="_blank" rel="noopener wikipedia">HTTP</a> server. License: GNU <a class="zem_slink" title="Affero General Public License" href="http://en.wikipedia.org/wiki/Affero_General_Public_License" target="_blank" rel="noopener wikipedia">AFFERO GENERAL PUBLIC LICENSE</a> Version 3.
-CRUD operations API on your data;
-Data model operations API: create databases, collections, indexes, and the data structure;
-Super easy setup, with convention over configuration approach;
-Pluggable security with User Management and ACL;
-<a class="reference external" href="http://en.wikipedia.org/wiki/Hypertext_Application_Language">HAL</a> hypermedia type;
-Super lightweight: pipeline architecture, ~6Mb footprint, ~200Mb RAM peak usage, starts in milliseconds;
-High throughput: very small overhead on MongoDB performance;
-Horizontally scalable: fully stateless architecture supporting MongoDB replica sets and shards;
-Built on top of Undertow non-blocking <a href="fronting-with-apache-httpd-jboss" target="_blank" rel="noopener">HTTP</a> server;
-Embeds the excellent HAL browser by Mike Kelly (the author of the HAL specifications);
-Supports <a class="zem_slink" title="Cross-origin resource sharing" href="http://en.wikipedia.org/wiki/Cross-origin_resource_sharing" target="_blank" rel="noopener wikipedia">Cross-Origin Resource Sharing</a> (CORS) so that your one-page web application can deal with RESTHeart running on a different domain. In other words, CORS is an evolution of <a class="reference external" href="http://en.wikipedia.org/wiki/JSONP">JSONP</a>;
-Ideal as AngularJS (or any other MVW Javascript framework) back-end.
<div id="drowsydromedary-ruby" class="section">
<h3>DrowsyDromedary (Ruby)</h3>
DrowsyDromedary is a REST layer for <a href="mongodb-limit" target="_blank" rel="noopener">MongoDB</a> based on Ruby.</div>
<div id="crest-node-js" class="section">
<h3>Crest (Node.jS)</h3>
The crest is a REST API Server for MongoDB built-in node.js using the MongoDB Node Native driver.</div>
<div id="amid" class="section">
<h3>AMID</h3>
AMID is a REST interface for MongoDB. Written in Node.js, supports multi-threading and a modular architecture to perform the custom search operation. AMID also provides an optional extjs GUI for queries:AMIDGUI.</div>
<div id="mongodb-java-rest-server" class="section">
<h3>Mongodb Java REST server</h3>
MongoDB Java REST server based on Jetty.</div>
<div id="kule" class="section">
<h3>Kule</h3>
Kule is a customizable REST interface for MongoDB based on <a href="tutorials-python" target="_blank" rel="noopener">Python</a>.
<div id="rest-interfaces" class="section">
<div id="dreamfactory" class="section">
<h3>DreamFactory</h3>
DreamFactory is an open source backend with a REST API for MongoDB. DreamFactory on GitHub.</div>
</div>
<div id="http-interfaces" class="section">
<h2>HTTP Interfaces</h2>
<div id="sleepy-mongoose-python" class="section">
<h3>Sleepy Mongoose (Python)</h3>
Sleepy Mongoose is a full featured HTTP interface for MongoDB.
<h2>HTTP Status Interface</h2>
<div class="deprecated">Deprecated since version 3.2: Starting in 3.2, MongoDB deprecates the HTTP interface.</div>
MongoDB provides a simple HTTP interface listing information of interest to administrators. If you enable the interface with the <code class="docutils literal">--rest</code> option to mongod&nbsp;you may access it via a port that is 1000 more than the configured mongod&nbsp;port. The default port for the HTTP interface is <code class="docutils literal">28017</code>. To access the HTTP interface an administrator may, for example, point a browser to <code class="docutils literal">http://localhost:28017</code> if mongod&nbsp;is running with the default port on the local machine. <img class=" wp-image-19405 aligncenter" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2016/05/Capture.5881.png" alt="Capture.588" width="745" height="686" /> Here is a description of the informational elements of the HTTP interface:
<table class="docutils" border="1"><colgroup> <col width="50%" /> <col width="50%" /></colgroup>
<thead valign="bottom">
<tr class="row-odd">
<th class="head">element</th>
<th class="head">description</th>
</tr>
</thead>
<tbody valign="top">
<tr class="row-even">
<td>db version</td>
<td>database version information</td>
</tr>
<tr class="row-odd">
<td>git hash</td>
<td>database version developer tag</td>
</tr>
<tr class="row-even">
<td>sys info</td>
<td><code class="xref mongodb mongodb-program docutils literal">mongod</code>&nbsp;compilation environment</td>
</tr>
<tr class="row-odd">
<td>dblocked</td>
<td>indicates whether the primary <code class="xref mongodb mongodb-program docutils literal">mongod</code>&nbsp;mutex is held</td>
</tr>
<tr class="row-even">
<td>uptime</td>
<td>time since this <code class="xref mongodb mongodb-program docutils literal">mongod&nbsp;</code>instance was started</td>
</tr>
<tr class="row-odd">
<td>assertions</td>
<td>any software assertions that have been raised by this<code class="xref mongodb mongodb-program docutils literal">&nbsp;mongod</code>&nbsp;instance</td>
</tr>
<tr class="row-even">
<td>replInfo</td>
<td>information about replication configuration</td>
</tr>
<tr class="row-odd">
<td>currentOp</td>
<td>most recent client request</td>
</tr>
<tr class="row-even">
<td># databases</td>
<td>number of databases that have been accessed by this&nbsp;<code class="xref mongodb mongodb-program docutils literal">mongod</code>&nbsp;instance</td>
</tr>
<tr class="row-odd">
<td>curclient</td>
<td>last database accessed by this <code class="xref mongodb mongodb-program docutils literal">mongod</code>&nbsp;instance</td>
</tr>
<tr class="row-even">
<td>Cursors</td>
<td>describes outstanding client cursors</td>
</tr>
<tr class="row-odd">
<td>master</td>
<td>whether this <code class="xref mongodb mongodb-program docutils literal">mongod</code>&nbsp;instance has been designated a master</td>
</tr>
<tr class="row-even">
<td>slave</td>
<td>whether this <code class="xref mongodb mongodb-program docutils literal">mongod</code>&nbsp;instance has been designated a slave</td>
</tr>
<tr class="row-odd">
<td>initialSyncCompleted</td>
<td>whether this slave or repl pair node has completed an initial clone of the <code class="xref mongodb mongodb-program docutils literal">mongod&nbsp;</code>instance it is replicating</td>
</tr>
<tr class="row-even">
<td>DBTOP</td>
<td>Displays the total time themongod&nbsp;instance has devoted to each listed collection, as well as the percentage of available time devoted to each listed collection recently and the number of reads, writes, and total calls made recently</td>
</tr>
<tr class="row-odd">
<td>dt</td>
<td>Timing information about the primary <code class="xref mongodb mongodb-program docutils literal">mongod&nbsp;</code>mutex</td>
</tr>
</tbody>
</table>
<pre style="text-align: center;">These core tutorials will help you to learn the fundamentals of Mongo DB. For an in-depth understanding and practical experience, explore Online <a href="https://tekslate.com/mongodb-training/" target="_blank" rel="noopener">Mongo DB Training</a>.</pre>
<h3>HTTP Status Interface Security</h3>
If security is configured for a <code class="xref mongodb mongodb-program docutils literal">mongod&nbsp;</code>instance, authentication is required for a client to access the HTTP status interface from another machine.
<h2>Simple REST API</h2>
The&nbsp;mongod&nbsp;process includes a simple REST API as a convenience. With no support for insert, update, or remove operations, it is generally used for monitoring, alert scripts, and administrative tasks. For full REST capabilities, consider using an external RESET interface&nbsp;&nbsp;such as Sleepy.Mongoose. v1.4+: This API is disabled by default, as it could provide unauthenticated access to data. Use <code class="docutils literal">--rest</code> on the command line to enable, but be aware of security implications. To get the contents of a collection (note the trailing slash):
http://127.0.0.1:28017/databaseName/collectionName/
To add a limit:
http://127.0.0.1:28017/databaseName/collectionName/?limit=-10
To skip:
http://127.0.0.1:28017/databaseName/collectionName/?skip=5
To query for <code class="docutils literal">{a : 1}</code>:
http://127.0.0.1:28017/databaseName/collectionName/?filter_a=1
Separate conditions with an <code class="docutils literal">&amp;</code>:
<div class="highlight-sh">
<div class="highlight">
<pre style="padding-left: 30px;">http://127.0.0.1:28017/databaseName/collectionName/?filter_a=1&amp;limit=-10
</pre>
</div>
</div>
Same as <code class="docutils literal">db.$cmd.findOne({listDatabase:1})</code> on the <code class="docutils literal">admin</code> database in the shell:
<div class="highlight-sh">
<div class="highlight">
<pre style="padding-left: 30px;">http://localhost:28017/admin/$cmd/?filter_listDatabases=1&amp;limit=1
</pre>
</div>
</div>
To count documents in a collection:
<div class="highlight-sh">
<div class="highlight">
<pre style="padding-left: 30px;">http://host:port/db/$cmd/?filter_count=collection&amp;limit=1</pre>
<h3>JSON in the simple REST API</h3>
The simple REST API uses strict JSON (as opposed to the shell, which uses Dates, regular expressions, etc.). To display non-JSON types, the web interface wraps them in objects and uses the key for the type. For example :
<pre style="padding-left: 30px;"># ObjectIds just become strings
"_id" : "4a8acf6e7fbadc242de5b4f3"
# dates
"date" : { "$date" : 1250609897802 }
# regular expressions
"match" : { "$regex" : "foo", "$options" : "ig" }
</pre>
The code type has not been implemented yet and causes the DB to crash if you try to display it in the browser. See Mongo Extended JSON for details.
<h2>Replica Set Admin UI</h2>
The <code class="xref mongodb mongodb-program docutils literal">mongod</code> the process includes a simple administrative UI for checking the status of a replica set. To use, first enable <code class="docutils literal">--rest</code> from the <code class="xref mongodb mongodb-program docutils literal">mongod</code> command line. The rest port is the db port plus 1000 (thus, the default is <code class="docutils literal">28017</code>). Be sure this port is secure before enabling this. Then you can navigate to <code class="docutils literal">http://&lt;hostname&gt;:28017/</code> in your web browser. Once there, click Replica Set Status (/_replSet) to move to the Replica Set Status page. <img class="alignnone size-full wp-image-19407" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2016/05/Capture.591.png" alt="Capture.591" width="783" height="422" />
&nbsp;
</div>
</div>
</div>
</div>
</div>
&nbsp;

MongoDB interface | MongoDB GUI 

MongoDB Interface

mongodb-interface

Using Select in MongoDB | Tekslate Online Trainings

Using Select in MongoDB

using-select-mongodb

<h2>The Limit() Method</h2>
To limit the records in <a href="mongodb-database" target="_blank" rel="noopener">MongoDB</a>, you need to use limit() method. limit()method accepts one number type argument, which is the number of documents that you want to display. The limit() function in <a href="https://tekslate.com/tutorials/mongodb-tutorials">MongoDB</a> is used to specify the maximum number of results to be returned. Only one parameter is required for this function.to return the number of the desired result. Sometimes it is required to return a certain number of results after a certain number of documents. The skip() can do this job.
<h3>Syntax:</h3>
Basic <a class="zem_slink" title="Syntax" href="http://en.wikipedia.org/wiki/Syntax" target="_blank" rel="noopener wikipedia">syntax</a> of limit() method is as follows
<pre class="prettyprint notranslate prettyprinted">&gt;db.COLLECTION_NAME.find().limit(NUMBER)</pre>
<h3>Example</h3>
Consider the collection myycol has the following data
<pre class="prettyprint notranslate prettyprinted">{ "_id" : ObjectId(5983548781331adf45ec5), "title":"MongoDB Overview"}
{ "_id" : ObjectId(5983548781331adf45ec6), "title":"<a class="zem_slink" title="NoSQL" href="http://en.wikipedia.org/wiki/NoSQL" target="_blank" rel="noopener wikipedia">NoSQL</a> Overview"}
{ "_id" : ObjectId(5983548781331adf45ec7), "title":"Tutorials Point Overview"}</pre>
Following example will display only 2 documents while quering the document.
<pre class="prettyprint notranslate prettyprinted">&gt;db.mycol.find({},{"title":1,_id:0}).limit(2)
{"title":"MongoDB Overview"}
{"title":"NoSQL Overview"}
&gt;
</pre>
If you don't specify the number argument in the limit() method then it will display all documents from the collection.
&nbsp;
<pre style="text-align: center;">Learn MongoDB by Tekslate - Fastest growing sector in the industry.Explore Online <a href="https://tekslate.com/mongodb-training/" target="_blank" rel="noopener">MongoDB Training</a> and course is aligned with industry needs &amp; developed by industry veterans.Tekslate will turn you into MongoDB Expert.</pre>
&nbsp;
<h2>MongoDB Skip() Method</h2>
Apart from the limit() method, there is one more method skip() which also accepts a number type argument and used to skip a number of documents.
<h3>Syntax:</h3>
The basic syntax of the skip() method is as follows
<pre class="prettyprint notranslate prettyprinted">&gt;db.COLLECTION_NAME.find().limit(NUMBER).skip(NUMBER)</pre>
<h3>Example:</h3>
The following example will only display only the second document.
<pre class="prettyprint notranslate prettyprinted">&gt;db.mycol.find({},{"title":1,_id:0}).limit(1).skip(1)
{"title":"NoSQL Overview"}
&gt;
Please note default value in skip() method is 0</pre>
For in-depth understanding click on
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MongoDB Limit - Tekslate

MongoDB Limit

mongodb-limit

<h2 style="text-align: justify;">Enabling Text Search:</h2>
Initially Text Search was an experimental feature but starting from version 2.6, the configuration is enabled by default. But if you are using previous version of <a href="https://tekslate.com/mongodb-training/">MongoDB</a>, you have to enable text search with following code:
<tt class="descclassname">db.collection.</tt><tt class="descname">find</tt><big>(</big>query, projection<big>)</big>
Selects documents in a collection and returns a cursor to the selected documents.
<h3 style="text-align: justify;">Find All Documents in a Collection</h3>
The <tt class="xref mongodb mongodb-method docutils literal">find()</tt> method with no parameters returns all documents from a collection and returns all fields for the documents. For example, the following operation returns all documents in the bios collection:
<pre>db.bios.find()</pre>
<h3 style="text-align: justify;">Find Documents that Match Query Criteria</h3>
To find documents that match a set of selection criteria, call <tt class="xref mongodb mongodb-method docutils literal">find()</tt> with the <tt class="docutils literal">&lt;criteria&gt;</tt> <a href="https://tekslate.com/tutorials/mongodb-tutorials">parameter</a>. The following operation returns all the documents from the collection <tt class="docutils literal">products</tt> where <tt class="docutils literal">qty</tt> is greater than <tt class="docutils literal">25</tt>:
<pre>db.products.find( { qty: { $gt: 25 } } )</pre>
<h4 style="text-align: justify;">Query for Equality</h4>
The following operation returns documents in the bios collection where <tt class="docutils literal">_id</tt> equals <tt class="docutils literal">5</tt>:
<pre>db.bios.find( { _id: 5 } )</pre>
<h4 style="text-align: justify;">Query Using Operators</h4>
The following operation returns documents in the <a href="https://tekslate.com/mongodb-limit/">bios collection </a>where <tt class="docutils literal">_id</tt> equals either <tt class="docutils literal">5</tt> or<tt class="docutils literal">ObjectId("507c35dd8fada716c89d0013")</tt>:
<pre>db.bios.find(
 {
 _id: { $in: [ 5, ObjectId("507c35dd8fada716c89d0013") ] }
 }
)</pre>
<h4 style="text-align: justify;">Query for Ranges</h4>
Combine <a class="zem_slink" title="Relational operator" href="http://en.wikipedia.org/wiki/Relational_operator" target="_blank" rel="noopener wikipedia">comparison operators</a> to specify ranges. The following operation returns documents with <tt class="docutils literal"><a class="zem_slink" title="Field (mathematics)" href="http://en.wikipedia.org/wiki/Field_%28mathematics%29" target="_blank" rel="noopener wikipedia">field</a>&nbsp;</tt>between <tt class="docutils literal">value1</tt> and <tt class="docutils literal">value2</tt>:
<div class="highlight-javascript">
<div class="highlight">
<pre>db.collection.find( { field: { $gt: value1, $lt: value2 } } );
</pre>
<h4 style="text-align: justify;">Query a Field that Contains an Array</h4>
If a field contains an array and your query has multiple conditional operators, the field as a whole will match if either a single <a class="zem_slink" title="Array data structure" href="http://en.wikipedia.org/wiki/Array_data_structure" target="_blank" rel="noopener wikipedia">array element</a> meets the conditions or a combination of array elements meet the conditions.
<pre style="text-align: center;">These core tutorials will help you to learn the fundamentals of Mongo DB.
For an in-depth understanding and practical experience, explore <a href="https://tekslate.com/mongodb-training/" target="_blank" rel="noopener">Online Mongo DB Training</a>.</pre>
</div>
<div class="highlight">
Given a collection <tt class="docutils literal">students</tt> that contains the following documents:
<div class="highlight-javascript" style="text-align: justify;">
<div class="highlight">
<pre>{ "_id" : 1, "score" : [ -1, 3 ] }
{ "_id" : 2, "score" : [ 1, 5 ] }
{ "_id" : 3, "score" : [ 5, 5 ] }</pre>
</div>
</div>
The following query:
<div class="highlight-javascript">
<div class="highlight">
<pre>db.students.find( { score: { $gt: 0, $lt: 2 } } )</pre>
Matches the following documents:
<div class="highlight-javascript" style="text-align: justify;">
<div class="highlight">
<pre>{ "_id" : 1, "score" : [ -1, 3 ] }
{ "_id" : 2, "score" : [ 1, 5 ] }</pre>
</div>
</div>
In the document with <tt class="docutils literal">_id</tt> equal to <tt class="docutils literal">1</tt>, the <tt class="docutils literal">score: [ -1, 3 ]</tt> meets the conditions because the element<tt class="docutils literal">-1</tt> meets the <tt class="docutils literal">$lt: 2</tt> condition and the element <tt class="docutils literal">3</tt> meets the <tt class="docutils literal">$gt: 0</tt> condition.
In the document with <tt class="docutils literal">_id</tt> equal to <tt class="docutils literal">2</tt>, the <tt class="docutils literal">score: [ 1, 5 ]</tt> meets the conditions because the element <tt class="docutils literal">1</tt>meets both the <tt class="docutils literal">$lt: 2</tt> condition and the <tt class="docutils literal">$gt: 0</tt> condition.
For indepth understanding click on
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<li class="title"><a href="https://tekslate.com/mongodb-index/" target="_blank" rel="noopener">MongoDB Index</a></li>
</ul>
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</div>
</div>
</div>

How to Find/Search Document in MongoDB | TekSlate MongoDB Tutorials

How to Find/Search Document in MongoDB

how-to-search-document-in-mongodb

<a href="https://tekslate.com/mongodb-training/">MongoDB</a> findAndModify() method modifies and returns a single document based upon the selection criteria entered. The returned document does not show the updated content by default. If the records matching the criteria does not exist in the database, a new record will be inserted if the <a class="zem_slink" title="Merge (SQL)" href="http://en.wikipedia.org/wiki/Merge_%28SQL%29" target="_blank" rel="noopener wikipedia">upsert</a> is set.
 syntax:
<pre>db.collection.findAndModify({
 query: &lt;document&gt;,
 sort: &lt;document&gt;, 
 new: &lt;boolean&gt;,
 fields: &lt;document&gt;,
 upsert: &lt;boolean&gt;
})</pre>
<h2 style="text-align: justify;">Find And Modify MongoDB</h2>
-If the entered selection criteria does not fetch any document and if upsert is set to true, then the specified values are inserted and a new document is created.
-If the entered selection criteria does not fetch any document while performing update or remove <a href="https://tekslate.com/mongodb-tutorials">operations</a>, the output returned is null.
-If the new option is set to false and sort operation is not mentioned, the output returned is null.
-If the new option is set to false and sort operation is specified, the output is empty.
Examples demonstrating the usage of the find And Modify <a class="zem_slink" title="Application programming interface" href="http://en.wikipedia.org/wiki/Application_programming_interface" target="_blank" rel="noopener wikipedia">API</a>.
Create some test data to start with.
create a new car document with name, color, car no (cno), speed and manufactured country(mfdcountry) fields through the mongo console.
<pre>db.car.insert(
[
{ _id: 1, name: "Alto", color: <a class="zem_slink" title="Red (Daniel Merriweather song)" href="http://en.wikipedia.org/wiki/Red_%28Daniel_Merriweather_song%29" target="_blank" rel="noopener wikipedia">"Red"</a>,cno: "H410",speed:40,mfdcountry: "India"},
{ _id: 2, name: "Polo", color: "<a class="zem_slink" title="Race and ethnicity in the United States Census" href="http://en.wikipedia.org/wiki/Race_and_ethnicity_in_the_United_States_Census" target="_blank" rel="noopener wikipedia">White</a>",cno: "H411",speed:45,mfdcountry: "Japan" },
{ _id: 3, name: "Audi", color: "Black",cno: "H412",speed:50,mfdcountry: "Germany" }
]
)</pre>
Verify that the data was actually inserted using find :
<pre>db.car.find()
{ "_id" : 1, "name" : "Alto", "color" : "Red", "cno" : "H410", "speed" : 40, "mfdcountry" : "India" }
{ "_id" : 2, "name" : "Polo", "color" : "White", "cno" : "H411", "speed" : 45, "mfdcountry" : "Japan" }
{ "_id" : 3, "name" : "Audi", "color" : "Black", "cno" : "H412", "speed" : 50, "mfdcountry" : "Germany" }</pre>
Moving on to the actual usage of find and modify, we depict different possibilities.
Case 1: The document exists in the database
<pre>db.car.findAndModify({
query: { name: "Alto" },
sort: { cno: 1 },
update: { $inc: { speed: 10 } },
})</pre>
The query finds a document in the car collection where the name field has the value Alto.
The sort orders the results of the query in ascending order. If multiple documents meet the query condition, the method will select for modification the first document as ordered by this sort.
<pre style="text-align: center;">Aspired to become an Mongo DB?
Explore the post to discover the know-hows on <a href="https://tekslate.com/mongodb-training/" target="_blank" rel="noopener">Mongo DB Training</a>.</pre>
The update increments the value of the speed field by 10.
The method returns the original document selected for this update :
Output:
<pre>{
"_id" : 1,
"name" : "Alto",
"color" : "Red",
"cno" : "H410",
"speed" : 40,
"mfdcountry" : "India"
}</pre>
Case 2: The new option set to true (returns the updated data set)
<pre>db.car.findAndModify({
query: { name: "HondaCity", color: "Silver", cno:"H415" ,speed: 25 },
sort: { cno: 1 },
update: { $inc: { speed: 20 } },
upsert: true,
new: true
})</pre>
Output:
<pre class="line number7 index6 alt2" style="text-align: justify;">{
"_id" : ObjectId("546c9f347256eabc40c9da1c"),
"cno" : "H415",
"color" : "Silver",
"name" : "HondaCity",
"speed" : 45
}</pre>
<div class="line number7 index6 alt2" style="text-align: justify;">Note: that speed is being displayed as 45 which is the updated value since we set new to be true. If this is not set, the speed field will be shown as 20 , the old value though it gets updated in the database.</div>
<div class="line number7 index6 alt2" style="text-align: justify;">&nbsp;</div>
<div class="line number7 index6 alt2" style="text-align: justify;">Case 3: The upsert is set to true</div>
<div class="line number7 index6 alt2" style="text-align: justify;">&nbsp;</div>
<pre class="line number7 index6 alt2">db.car.findAndModify({
query: { name: "WagonR" },
sort: { cno: 1 },
update: { $inc: { speed: 5 } },
upsert: &lt;strong&gt;true&lt;/strong&gt;
})</pre>
<div class="line number7 index6 alt2" style="text-align: justify;">&nbsp;</div>
<div class="line number7 index6 alt2" style="text-align: justify;">Output:</div>
<pre class="line number7 index6 alt2">db.car.find();
{ "_id" : 1, "name" : "Alto", "color" : "Red", "cno" : "H410", "speed" : 50, "mfdcountry" : "India" }
{ "_id" : 2, "name" : "Polo", "color" : "White", "cno" : "H411", "speed" : 45, "mfdcountry" : "Japan" }
{ "_id" : 3, "name" : "Audi", "color" : "Black", "cno" : "H412", "speed" : 50, "mfdcountry" : "Germany" }
{ "_id" : ObjectId("546c7c7d6be0faf69ee36546"), "name" : "WagonR", "speed" : 5 }</pre>
<div class="line number7 index6 alt2" style="text-align: justify;">&nbsp;</div>
<div class="line number7 index6 alt2" style="text-align: justify;">The car name with WagonR is not in the db hence a new document is created in <a href="https://tekslate.com/mongodb-database/">database</a>. The method returns an empty document { } if the sort option is specified. If sort option is not included then the method returns null.</div>
<div class="line number7 index6 alt2" style="text-align: justify;">&nbsp;</div>
<div class="line number7 index6 alt2">
Apart from these, this can also be used for doing a Sort and Remove operation.
If the remove field is set to true, the car name with the specified criteria will be removed from the database.
<pre>db.car.findAndModify(
{
query: { name: "Alto" },
sort: { cno: 1 },
remove: true
}
)</pre>
Output:
<pre>{
"_id" : 1,
"name" : "Alto",
"color" : "Red",
"cno" : "H410",
"speed" : 50,
"mfdcountry" : "India"
}</pre>
The remove field is set to true the document with the name &ldquo;Alto&rdquo; gets deleted from the database.
For indepth understanding click on
<ul>
<li class="title"><a class="current-page" href="https://tekslate.com/tutorials/mongodb-tutorials">MongoDB Tutorials</a></li>
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<li class="title"><a href="https://tekslate.com/using-select-mongodb/" target="_blank" rel="noopener">Using Select in MongoDB</a></li>
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Find and Modify in MongoDB | Tekslate MongoDB Tutorials

Find and Modify in MongoDB

modify-and-find-mongodb

<h2 class="post-title entry-title" style="text-align: justify;">How to sort document in MongoDB</h2>
The sort() Method
We need to use sort() method to sort documents in <a href="https://tekslate.com/mongodb-training/">MongoDB</a> , it accepts a document field along with their sorting order. To specify sorting order 1 and -1 are used. 1 is used for ascending order while -1 is used for descending order.
Syntax:
Basic syntax of sort() method is given below
<blockquote>db.COLLECTION_NAME.find().sort({KEY:1})</blockquote>
Example: Point out the collection test Col has the following data
<pre>{ "_id" : ObjectId(5983548781331adf45ec5), "title":"MongoDB Overview", "by":"codefari.com"}
{ "_id" : ObjectId(5983548781331adf45ec6), "title":" ASP.Net Over view ", "by":"codefari.com"}
{ "_id" : ObjectId(5983548781331adf45ec7), "title":" SQL Server 2014", "by":"codefari.com"}</pre>
Following example will display the documents sorted by title in descending order.
<pre style="text-align: center;">Learn MongoDB by Tekslate - Fastest growing sector in the industry.
Explore Online <a href="https://tekslate.com/mongodb-training/" target="_blank" rel="noopener">MongoDB Training</a> and course is aligned with industry needs &amp; developed by industry veterans.
Tekslate will turn you into MongoDB Expert.</pre>
<pre>&gt;db.testCol.find({},{"title":1,_id:0}).sort({"title":-1})
{"title":" SQL Server 2014"}
{"title":" MongoDB Overview "}
{"title":" SQL Server 2014"}
&gt;</pre>
Note:&nbsp;if you don't specify the <a href="https://tekslate.com/mongodb-tutorials">sorting </a>preference, then sort() method will display documents in ascending order.
<div class="tags">&nbsp;</div>

How to Sort document in MongoDB?

How to sort document in MongoDB

sort-document-mongodb

<h2 class="title entry-title" style="text-align: justify;">MongoDB where clause to query array length</h2>
There is no direct way in MongoDB to return all the documents where a sub-collection has at least X number of entries.
<pre class="language-markup"><code>{
 "name" : "Terry Brooks",
 "books" : [
 "The Sword of Shannara",
 "The Elfstones of Shannara",
 "The Wishsong of Shannara"
 ]
 },
 {
 "name" : "Oscar Wilde",
 "books" : [
 "The Picture of Dorian Gray"
]
 }</code></pre>
There is no direct way in MongoDB to do this. it needs to be done either by map-reduce or perhaps with the new aggregation framework but you cannot combine $gt and $size operators like so :
<pre class="brush:js" style="text-align: justify; padding-left: 30px;">db.AUTHORS.find({"books" : {$size : {$gt : 1}}});
</pre>
<table style="border-collapse: collapse; width: 100.017%; height: 29.0374px; background-color: #ecf0f1;" border="1px" cellpadding="10">
<tbody>
<tr style="height: 29.0374px;">
<td style="width: 98.3494%; height: 29.0374px; text-align: center;">Interested in mastering <a style="color: #236fa1;" href="https://tekslate.com/mongodb-training/" target="_blank">MongoDB Training</a>? Check out this blog post to learn more about MongoDB Tutorials.</td>
</tr>
</tbody>
</table>
<pre style="text-align: center;"> </pre>
It doesn't work, you won't get any <a class="zem_slink" title="Error message" href="http://en.wikipedia.org/wiki/Error_message" target="_blank" rel="noopener wikipedia">error messages</a> but an empty result. MongoDB allows Javascript evaluation through the <a href="http://www.mongodb.org/display/DOCS/Server-side+Code+Execution#Server-sideCodeExecution-%7B%7B%24where%7D%7DClausesandFunctionsinQueries" target="_blank">$where</a> operator although it's significantly slower than native operators it's very flexible and a quick way of executing a query without using MapReduce or other means :
<pre class="brush:js">db.AUTHORS.find({$where : "this.books.length &gt; 1"});
</pre>
But when this query was executed the following error kept coming up :
<pre class="language-markup"><code>{
 "error": {
 "$err": "erroroninvocationof$wherefunction: JSError: TypeError: this.bookshasnopropertiesnofile_a: 0",
 "code": 10071
 }
 }</code></pre>
The error is not very helpful (at least to me) and as it turns out the origin of the problem was the fact that not all Author documents in my database had the "books" array. So in order to execute a length query on the "books" array it's necessary to ensure that the array field (books) exists :
<pre class="brush:js"> db.AUTHORS.find({"books" : {$exists: true}, $where : "this.books.length &gt; 0"});</pre>
For in-depth understanding click on
<ul>
<li class="title"><a class="current-page" href="https://tekslate.com/mongodb-tutorials">MongoDB Tutorials</a></li>
<li class="title"><a class="current-page" href="https://tekslate.com/installation-of-mongodb/">How to install MongoDB</a></li>
<li class="title"><a href="https://tekslate.com/using-select-mongodb/" target="_blank">Using Select in MongoDB</a></li>
<li class="title"><a href="https://tekslate.com/collections-in-mongodb/" target="_blank">Collections in MongoDB</a></li>
<li class="title"><a href="https://tekslate.com/mongodb-index/" target="_blank">MongoDB Index</a></li>
</ul>