Unique Index

      If we create a Unique index on a table. Index will not allow duplicate values.

Example:

CREATE TABLE SAMPLE12

(

ID INT ,

NAME VARCHAR(10),

TYPE_DESC VARCHAR(50)

)

Syntax:

CREATE UNIQUE INDEX <Index Name> ON <Table Name> (<Column Name>)

Creating index on single column:

CREATE UNIQUE INDEX IDX_SAMPLE12_UQ ON SAMPLE12 (ID)

Result:

Drop Index:

DROP INDEX SAMPLE12.IDX_SAMPLE12_UQ

Result:

Creating index on multiple column:

CREATE UNIQUE INDEX IDX_SAMPLE12_UQ ON SAMPLE12 (ID,NAME)

Result:

Drop Index:

DROP INDEX SAMPLE12.IDX_SAMPLE12_UQ

Result: