ALTER表-在MySQL中添加AUTOINCREMENT [英] ALTER table - adding AUTOINCREMENT in MySQL

问题描述

我在MySQL中用itemID列创建了一个表.创建表后，现在我想将此列更改为AUTOINCREMENT.如何使用ALTER语句完成此操作?

I created a table in MySQL with on column itemID. After creating the table, now I want to change this column to AUTOINCREMENT. How can this be done using ALTER statements?

表定义:

ALLITEMS (itemid int(10) unsigned, itemname varchar(50))

我正在使用以下代码，但它抛出错误:语法错误.

I am using the following code but it is throwing error: syntax incorrect.

ALTER TABLE allitems
MODIFY itemid INT(10) UNSIGNED AUTOINCREMENT; 

推荐答案

CREATE TABLE ALLITEMS(
    itemid INT(10)UNSIGNED,
    itemname VARCHAR(50)
);

ALTER TABLE ALLITEMS CHANGE itemid itemid INT(10)AUTO_INCREMENT PRIMARY KEY;

DESC ALLITEMS;

INSERT INTO ALLITEMS(itemname)
VALUES
    ('Apple'),
    ('Orange'),
    ('Banana');

SELECT
    *
FROM
    ALLITEMS;

我之前也对CHANGE和MODIFY关键字感到困惑:

I was confused with CHANGE and MODIFY keywords before too:

ALTER TABLE ALLITEMS CHANGE itemid itemid INT(10)AUTO_INCREMENT PRIMARY KEY;

ALTER TABLE ALLITEMS MODIFY itemid INT(5);

在我们那里的同时，还请注意AUTO_INCREMENT也可以以预定义的数字开头:

While we are there, also note that AUTO_INCREMENT can also start with a predefined number:

ALTER TABLE tbl AUTO_INCREMENT = 100;

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