DROP INDEX

Grammar Description

This statement is used to delete the index from the currently selected table, and an error will be reported if the index does not exist unless the IF EXISTS modifier is used.

Grammar Structure

> DROP INDEX index_name ON tbl_name

Example

create table t5(a int, b int, unique key(a));
mysql> show create table t5;
+------------------------------------------------------------------------------------------------------------------------------
| Table | Create Table |
+------------------------------------------------------------------------------------------------------------------------------
| t5 | CREATE TABLE `t5` (
`a` INT DEFAULT NULL,
`b` INT DEFAULT NULL,
UNIQUE KEY `a` (`a`)
) |
+------------------------------------------------------------------------------------------------------------------------------
1 row in set (0.01 sec)

create index b on t5(b);
mysql> show create table t5;
+------------------------------------------------------------------------------------------------------------------------------
| Table | Create Table |
+------------------------------------------------------------------------------------------------------------------------------
| t5 | CREATE TABLE `t5` (
`a` INT DEFAULT NULL,
`b` INT DEFAULT NULL,
UNIQUE KEY `a` (`a`),
KEY `b` (`b`)
) |
+------------------------------------------------------------------------------------------------------------------------------
1 row in set (0.02 sec)

drop index b on t5;
mysql> show create table t5;
+------------------------------------------------------------------------------------------------------------------------------
| Table | Create Table |
+------------------------------------------------------------------------------------------------------------------------------
| t5 | CREATE TABLE `t5` (
`a` INT DEFAULT NULL,
`b` INT DEFAULT NULL,
UNIQUE KEY `a` (`a`)
) |
+------------------------------------------------------------------------------------------------------------------------------
1 row in set (0.02 sec)