How to change a primary key in SQL to auto_increment?
- by Jian Lin
I have a table in MySQL that has a primary key:
mysql> desc gifts;
+---------------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+---------------+-------------+------+-----+---------+-------+
| giftID | int(11) | NO | PRI | NULL | |
| name | varchar(80) | YES | | NULL | |
| filename | varchar(80) | YES | | NULL | |
| effectiveTime | datetime | YES | | NULL | |
+---------------+-------------+------+-----+---------+-------+
but I wanted to make it auto_increment.
The following statement failed. How can it be modified so that it can work? thanks
mysql> alter table gifts modify giftID int primary key auto_increment;
ERROR 1068 (42000): Multiple primary key defined
