我们可以从MySQL表中删除主键吗？
是的，我们可以使用MySQL中的DROP删除主键。以下是语法-
alter table yourTableName drop primary key;
让我们首先创建一个表-
mysql> create table DemoTable
(
UserId int NOT NULL PRIMARY KEY
);以下是查询以检查表的描述-
mysql> desc DemoTable;
这将产生以下显示主键的输出-
+--------+---------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +--------+---------+------+-----+---------+-------+ | UserId | int(11) | NO | PRI | NULL | | +--------+---------+------+-----+---------+-------+ 1 row in set (0.01 sec)
以下是从表中删除主键的查询-
mysql> alter table DemoTable drop primary key; Records: 0 Duplicates: 0 Warnings: 0
让我们再次检查表的描述-
mysql> desc DemoTable;
这将产生以下输出。现在主键不可见-
+--------+---------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +--------+---------+------+-----+---------+-------+ | UserId | int(11) | NO | | NULL | | +--------+---------+------+-----+---------+-------+ 1 row in set (0.01 sec)