Converting NOPI to PI table

Converting NOPI to PI table

There are 2 steps a) Create a multi set table with the same structure and take a primary index on that table. Create a multi set table New-tet(Party id integer, party name Varchar(30)primary index(Party id) b)Insert data into new- tet, drop tet table and rename new-tet to tet   i)Insert into new- tet select* from tet ii) drop table tet iii) Rename table new –tet to tet Altering a primary index(it table is empty and it is not having NOPI) Alter table test modify primary index(Party name)   Default primary Index If we don’t take and index on the table the system creats a primary index in the below process

1.  The unique key(or) primary key column consider as UPI
2.  IF No unique kdy (or) primary key it create on the first column NOPI.

  Note If both primary key and unique key columns available it takes primary index(PI)on primary key column and (Unique primary index) and unique columns as USI(Secondary index)     

Difference between primary index and primary key

Primary index(P.I)	Primary key (P.K)
Primary index mandatory	Primary key optional
Max 64 Columns combination	No limit on no. of columns to composite
effects data distribution	Doesn’t effect data distribution
can take duplications and null	Doesn’t allow null and duplicates.
physical mechanism	Logical mechanism
Cannot be drop	Cannot be drop
Queries stores and retrieve faster w.r.to PI etc….