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是否必须将PRIMARY KEY设置为AUTO_INCREMENT值？

2024-04-26 00:59:15 348

是的，将AUTO_INCREMENT与PRIMARYKEY一起使用。让我们首先创建一个表-

mysql> create table DemoTable
(
   EmployeeId int NOT NULL AUTO_INCREMENT,
   EmployeeName varchar(40),
   EmployeeAge int,
   PRIMARY KEY(EmployeeId),
   UNIQUE KEY(EmployeeName,EmployeeAge)
);

让我们检查表的表说明-

mysql> desc DemoTable;

这将产生以下输出-

+--------------+-------------+------+-----+---------+----------------+
| Field        | Type        | Null | Key | Default | Extra          |
+--------------+-------------+------+-----+---------+----------------+
| EmployeeId   | int(11)     | NO   | PRI | NULL    | auto_increment |
| EmployeeName | varchar(40) | YES  | MUL | NULL    |                |
| EmployeeAge  | int(11)     | YES  |     | NULL    |                |
+--------------+-------------+------+-----+---------+----------------+
3 rows in set (0.17 sec)

使用插入命令在表中插入一些记录-

mysql> insert into DemoTable(EmployeeName,EmployeeAge) values('Chris',25);
mysql> insert into DemoTable(EmployeeName,EmployeeAge) values('Robert',34);
mysql> insert into DemoTable(EmployeeName,EmployeeAge) values('Mike',32);

使用select语句显示表中的所有记录-

mysql> select *from DemoTable;

这将产生以下输出-

+------------+--------------+-------------+
| EmployeeId | EmployeeName | EmployeeAge |
+------------+--------------+-------------+
|          1 | Chris        |          25 |
|          3 | Mike         |          32 |
|          2 | Robert       |          34 |
+------------+--------------+-------------+
3 rows in set (0.00 sec)

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是否必须将PRIMARY KEY设置为AUTO_INCREMENT值？

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