如何在MySQL中删除主键？
要删除主键，请首先使用ALTER更改表。这样，使用DROP删除键，如下所示
语法
alter table yourTableName drop primary key;
让我们首先创建一个表-
mysql> create table DemoTable -> ( -> StudentId int NOT NULL, -> StudentName varchar(20), -> StudentAge int, -> primary key(StudentId) -> );
这是检查表说明的查询-
mysql> desc DemoTable;
+-------------+-------------+------+-----+---------+-------+ | 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; 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)
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