在MySQL中设置AUTO_INCREMENT字段的起始值

Question

我在数据库中创建表有一个简单的问题.这是我的代码:

$query="CREATE TABLE users (
    userid int(5) not null AUTO_INCREMENT, 
    firstname varchar(20),
    lastname varchar(20),
    username varchar(30),
    password varchar(32),
    email varchar(50),
    age int(2),
    PRIMARY KEY (userid)
)";

我希望从一USERID AUTO INCREMENT开始SPECIFIC NUMBER.

例如,从99001开始......

我怎样才能做到这一点？

Answer 1

您有两种方法来设置AUTO_INCREMENT字段的起始值.ALTER TABLE如果您的表已经存在,您可以调用以下命令:

ALTER TABLE users AUTO_INCREMENT = 99001;

否则,您也可以直接在CREATE TABLE命令中使用设置起始值,如下所示:

CREATE TABLE users (
   userid int(5) not null AUTO_INCREMENT, 
   firstname varchar(20),
   lastname varchar(20),
   username varchar(30),
   password varchar(32),
   email varchar(50),
   age int(2),
   PRIMARY KEY (userid)
) AUTO_INCREMENT = 99001;

测试用例:

CREATE TABLE users (
   userid int(5) not null AUTO_INCREMENT, 
   firstname varchar(20),
   lastname varchar(20),
   username varchar(30),
   password varchar(32),
   email varchar(50),
   age int(2),
   PRIMARY KEY (userid)
);
Query OK, 0 rows affected (0.04 sec)

ALTER TABLE users AUTO_INCREMENT = 99001;
Query OK, 0 rows affected (0.05 sec)

INSERT INTO users (firstname, lastname, username, password) 
           VALUES ('a', 'b', 'c', 'd');
Query OK, 1 row affected (0.00 sec)

SELECT * FROM users;
+--------+-----------+----------+----------+----------+-------+------+
| userid | firstname | lastname | username | password | email | age  |
+--------+-----------+----------+----------+----------+-------+------+
|  99001 | a         | b        | c        | d        | NULL  | NULL |
+--------+-----------+----------+----------+----------+-------+------+
1 row in set (0.00 sec)