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如何在单个MySQL查询中更改多个列的列类型？

2024-05-18 20:12:07 386

要更改单个MySQL查询中多个列的列类型，语法如下-

alter table yourTableName
modify column yourColumnName 1 yourDataType1,
modify column yourColumnName 2 yourDataType2,
.
.
N;

让我们首先创建一个表-

create table DemoTable
(
   Id varchar(100),
   FirstName text,
   LastName text
);

让我们检查表的描述-

desc DemoTable;

这将产生以下输出-

+-----------+--------------+------+-----+---------+-------+
| Field     | Type         | Null | Key | Default | Extra |
+-----------+--------------+------+-----+---------+-------+
| Id        | varchar(100) | YES  |     | NULL    |       |
| FirstName | text         | YES  |     | NULL    |       |
| LastName  | text         | YES  |     | NULL    |       |
+-----------+--------------+------+-----+---------+-------+
3 rows in set (0.09 sec)

以下是更改多个列的列类型的查询。在这里，我们更改了Id，FirstName和LastName列的列类型-

alter table DemoTable
   modify column Id int,
   modify column FirstName varchar(50),
   modify column LastName varchar(50);
Records: 0 Duplicates: 0 Warnings: 0

让我们再次检查表的描述-

desc DemoTable;

这将产生以下输出-

+-----------+-------------+------+-----+---------+-------+
| Field     | Type        | Null | Key | Default | Extra |
+-----------+-------------+------+-----+---------+-------+
| Id        | int(11)     | YES   |    | NULL    |       |
| FirstName | varchar(50) | YES   |    | NULL    |       | 
| LastName  | varchar(50) | YES   |    | NULL    |       |
+-----------+-------------+------+-----+---------+-------+
3 rows in set (0.00 sec)

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如何在单个MySQL查询中更改多个列的列类型？

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