MySQL 我们能从MySQL表中移除主键吗？

是的，我们可以使用MySQL中的DROP从数据库中移除主键。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
   );
Query OK, 0 rows affected (0.58 sec)

以下是检查表描述的查询 –

mysql> desc DemoTable;

这将产生以下输出，显示主键 –

+--------+---------+------+-----+---------+-------+
| 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;
Query OK, 0 rows affected (1.51 sec)
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。现在主键不可见了 –

+--------+---------+------+-----+---------+-------+
| Field  | Type    | Null | Key | Default | Extra |
+--------+---------+------+-----+---------+-------+
| UserId | int(11) | NO   |     | NULL    |       |
+--------+---------+------+-----+---------+-------+
1 row in set (0.01 sec)

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