如何在 MySQL 中删除主键?
mysqlmysqli database
要删除主键，首先使用 ALTER 更改表。然后，使用 DROP 删除键，如下所示
语法
alter table yourTableName drop primary key;
首先我们创建一个表 −
mysql> create table DemoTable -> ( -> StudentId int NOT NULL, -> StudentName varchar(20), -> StudentAge int, -> primary key(StudentId) -> ); Query OK, 0 rows affected (0.48 sec)
这是检查表描述的查询 −
mysql> desc DemoTable;
这将产生以下输出 −
+-------------+-------------+------+-----+---------+-------+ | 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)
以下是在 MySQL 中删除主键的查询 −
mysql> alter table DemoTable drop primary key; Query OK, 0 rows affected (1.70 sec) Records: 0 Duplicates: 0 Warnings: 0
让我们再次检查表描述 −
mysql> desc DemoTable;
这将产生以下输出 −
+-------------+-------------+------+-----+---------+-------+ | 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)
