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How can we remove PRIMARY KEY constraint from a column of an existing MySQL table?
We can remove PRIMARY KEY constraint from a column of an existing table by using DROP keyword along with ALTER TABLE statement.
Example
Suppose we have a table ‘Player’ having a PRIMARY KEY constraint on column ‘ID’ as follows −
mysql> DESCRIBE Player; +-------+-------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-------+-------------+------+-----+---------+-------+ | ID | int(11) | NO | PRI | NULL | | | Name | varchar(20) | YES | | NULL | | +-------+-------------+------+-----+---------+-------+ 2 rows in set (0.04 sec)
Now if we want to remove the PRIMARY KEY constraint then we can use ALTER TABLE statement as follows −
mysql> alter table Player DROP PRIMARY KEY; Query OK, 0 rows affected (0.31 sec) Records: 0 Duplicates: 0 Warnings: 0 mysql> DESCRIBE Player; +-------+-------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-------+-------------+------+-----+---------+-------+ | ID | int(11) | NO | | NULL | | | Name | varchar(20) | YES | | NULL | | +-------+-------------+------+-----+---------+-------+ 2 rows in set (0.04 sec)
The above result set shows that PRIMARY KEY constraint on column ‘ID’ has been removed.
Updated on: 19-Jun-2020
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