Home > Database > Mysql Tutorial > body text

How can we remove PRIMARY KEY constraint from column of existing MySQL table?

WBOY
Release: 2023-09-01 17:45:06
forward
1017 people have browsed it

我们如何从现有 MySQL 表的列中删除 PRIMARY KEY 约束?

We can remove PRIMARY KEY constraints from columns of existing tables by using DROP keyword and ALTER TABLE statement.

Example

Suppose we have a table "Player" with a primary key constraint on the "ID" column 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) 
Copy after login

Now, if we want to delete PRIMARY KEY constraint, then we can use ALTER TABLE statement as shown below-

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) 
Copy after login

The above result set shows that the PRIMARY KEY constraint on column "ID" has been deleted.

The above is the detailed content of How can we remove PRIMARY KEY constraint from column of existing MySQL table?. For more information, please follow other related articles on the PHP Chinese website!

source:tutorialspoint.com
Statement of this Website
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn
Popular Tutorials
More>
Latest Downloads
More>
Web Effects
Website Source Code
Website Materials
Front End Template