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我們如何將AUTO_INCREMENT應用到一列上?

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2023-08-24 10:21:04671瀏覽

我們如何將AUTO_INCREMENT應用到一列上?

AUTO_INCREMENT表示該欄位將自動取得值。為了說明這一點,我們建立了一個名為「employees」的表,如下所示:

mysql> Show Create Table employees\G

*************************** 1. row ***************************
Table: employees

Create Table: CREATE TABLE `employees` (
   `Id` int(11) NOT NULL AUTO_INCREMENT,
   `Name` varchar(35) DEFAULT NULL,
   PRIMARY KEY (`Id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1

1 row in set (0.00 sec)

從上面的結果集中,我們可以看到id列被賦予了自動遞增選項。現在,當我們在Name欄位中插入值時,id欄位會自動取得值−

mysql> Insert Into employees(Name) Values('Ram');
Query OK, 1 row affected (0.09 sec)

mysql> Insert Into employees(Name) Values('Shyam');
Query OK, 1 row affected (0.03 sec)

mysql> Insert Into employees(Name) Values('Mohan');
Query OK, 1 row affected (0.04 sec)

mysql> Insert Into employees(Name) Values('Sohan');
Query OK, 1 row affected (0.04 sec)

mysql> Select * from employees;

+----+-------+
| Id | Name  |
+----+-------+
| 1  | Ram   |
| 2  | Shyam |
| 3  | Mohan |
| 4  | Sohan |
+----+-------+

4 rows in set (0.00 sec)

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