SQL CREATE UNIQUE INDEX keyword usage and example

SQL Keywords Reference

CREATE UNIQUE INDEX (Create a unique index)

The CREATE UNIQUE INDEX command creates a unique index on the table (does not allow duplicate values)

Indexes are used to retrieve data from the database very quickly. Users do not see indexes; they are only used to speed up searches/Query.

The following SQL creates an index named 'uidx_pid' on the 'PersonID' column of the 'Persons' table:

CREATE UNIQUE INDEX uidx_pid
ON Persons (PersonID);

Note:The syntax for creating indexes varies between databases. Therefore: Check the syntax used to create indexes in the database.

SQL Keywords Reference