10 October, 2020
Oracle PL/SQL is a procedural language that has both interactive SQL and procedural programming language constructs such as iteration, conditional branching.
PL/SQL uses block structure as its basic structure. Anonymous blocks or nested blocks can be used in PL/SQL.
A list of some notable characteristics:
The compilation process includes syntax check, bind, and p-code generation processes. Syntax checking checks the PL/SQL codes for compilation errors. When all errors are corrected, a storage address is assigned to the variables that hold data. It is called Binding. P-code is a list of instructions for the PL/SQL engine. P-code is stored in the database for named blocks and is used the next time it is executed.
Before getting into the PL/SQL, we must create a REST API using JSON for establishing connections. You can import the Retrofit libraries along with dependencies to establish communication with your Android App. Then prepare the functions and procedures using PL/SQL, and then once your oracle database is connected.
Stored procedures and functions
|Query/Command executions||Programming Language Execution at a time|
|The data source for web pages||Build, format, and display web pages that contain data source|
|Declarative in nature||Procedural in nature|
|Manipulating data||Creating Web Applications|
A trigger is a PL/SQL program that is stored in the database and executed immediately before or after the INSERT, updates, and deletes commands.
Basically, triggers are used to create consistencies, access restrictions, and implement securities to the database. Triggers are also used for −
We can make use of the DBMS_OUTPUT for printing breakpoint activities. We can also use DBMS_DEBUG.
We cannot. It is not logical to put a Rollback or Commit within a Trigger because these statements impose a savepoint that affects the logical transaction processing.
A sequence generates a serial list of unique numbers for numerical columns of a database's tables.
INSTR (String1, String2 (n, (m)), INSTR returns the position of the m-th occurrence of the string 2 in string1. The search begins from the nth position of string1.
SUBSTR (String1 n, m) SUBSTR returns a character string of size m in string1, starting from an n-th position of string1.
PS/SQL Records is a type of data structure that contains a set of data(can be of various types), or distinct information values that can be referenced with each other as fields. They are useful for classifying and retrieving data with common attributes or properties. With this, it is much easier to identify similar data by tracing the attributes.
PL/SQL can manage three types of records:
We make use of the DECODE keyword. For example, e.g. select DECODE (EMP_CAT,’3′,’Third’,’4′,fourth null);
Oracle database is comprised of three types of files. One or more datafiles, two are more redo log files, and one or more control files.
CALL <procedure name> to call it directly
EXECUTE <procedure name> from calling environment
<Procedure name> from other procedures or functions or packages
Functions are called directly from other programs or procedures, no additional keyword is required.
PL SQL data types can be broadly divided into the following categories. There are many data types available in PL SQL but mostly you will be using some of the popular ones.
|STARTUP NOMOUNT||Instance startup|
|STARTUP MOUNT||The database is mounted|
|STARTUP OPEN||The database is opened|
Using ‘J’ format string
SQL > select to_char(to_date(’24-Jan-2013′,’dd-mm-yyyy’),’J’) as julian from dual;
What is meant by Exception Handling in PL/SQL and what are its distinct types? The exception is raised in PL/SQL whenever an error occurs. In other words, these are raised to handle undesired situations where PL/SQL scripts terminated unexpectedly including an error handling code in the program. Exception Section in PL/SQL contains this exception handling code. There are 3 types of Exception: Predefined Exceptions: General Errors with pre-defined names Undefined Exceptions: Less common errors and are not pre-defined User-defined Exceptions: Violates business rules but don’t disturb running Discuss PL/SQL Records? The collection of PL/SQL server training Hyderabad is referred as the collection of values or information that is divided into multiple pieces, each of which is of simpler types and related to one another as fields. There are three types of records supported in PL/SQL
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