2. Unique Index : It is applied to an individual column in a table. It does not allow duplicate entries; this prevents the same data from being entered again. For example, if you have a table named student with four columns: class, roll_no, and email_id, and you apply a unique index to the email_id column, it will prevent duplicate email addresses from being entered.
Syntax:
CREATE UNIQUE INDEX index_name ON table_name(column_name);