MySQL INDEX Constraint

In MySQL, INDEX constraint are used to speed up data retrieval from database table. To create INDEX in MySQL, CREATE INDEX statement is used to create indexes in tables. MySQL allows to create multiple-column INDEX.

MySQL INDEX Syntax

To create indexes in tables using CREATE INDEX statement, use the following syntax:

CREATE INDEX indexname
ON tablename (col1);

Parameters:

indexname: Name of the INDEX, you want to create.

tablename: The table name from which you want to fetch records.

col1: The column name on which you want to create index.

MySQL INDEX Constraint example

CREATE INDEX idex_custId
ON tblCustomer (custId);

MySQL UNIQUE INDEX Syntax

CREATE UNIQUE INDEX indexname
ON tablename (col1);

MySQL UNIQUE INDEX Constraint example

CREATE UNIQUE INDEX idex_custId
ON tblCustomer (custId);

MySQL DROP a INDEX Constraint example

ALTER TABLE tblCustomer
DROP INDEX idex_custId;