How do I drop a primary key in MySQL?

To drop a primary key, use ALTER at first to alter the table. With that, use DROP to drop the key as in the below

Syntax

alter table yourTableName drop primary key;

Let us first create a table −

mysql> create table DemoTable    -> (    -> StudentId int NOT NULL,    -> StudentName varchar(20),    -> StudentAge int,    -> primary key(StudentId)    -> ); Query OK, 0 rows affected (0.48 sec)

Here is the query to check the description of table −

mysql> desc DemoTable;

This will produce the following output−

+-------------+-------------+------+-----+---------+-------+ | Field       | Type        | Null | Key | Default | Extra | +-------------+-------------+------+-----+---------+-------+ | StudentId   | int(11)     | NO   | PRI | NULL    |       | | StudentName | varchar(20) | YES  |     | NULL    |       | | StudentAge  | int(11)     | YES  |     | NULL    |       | +-------------+-------------+------+-----+---------+-------+ 3 rows in set (0.00 sec)

Following is the query to drop a primary key in MySQL −

mysql> alter table DemoTable drop primary key; Query OK, 0 rows affected (1.70 sec) Records: 0 Duplicates: 0 Warnings: 0

Let us check the table description once again −

mysql> desc DemoTable;

This will produce the following output −

+-------------+-------------+------+-----+---------+-------+ | Field       | Type        | Null | Key | Default | Extra | +-------------+-------------+------+-----+---------+-------+ | StudentId   | int(11)     | NO   |     | NULL    |       | | StudentName | varchar(20) | YES  |     | NULL    |       | | StudentAge  | int(11)     | YES  |     | NULL    |       | +-------------+-------------+------+-----+---------+-------+ 3 rows in set (0.00 sec)