如何在MySQL表中移动列? [英] How to move columns in a MySQL table?

问题描述

当前，我有以下MySQL表:Employees (empID, empName, department);

Currently I am having the following MySQL table: Employees (empID, empName, department);

我要将表更改为以下内容:Employees (empID, department, empName);

I want to change the table to the following: Employees (empID, department, empName);

如何使用ALTER语句完成此操作?

How can this be done using ALTER statements?

注意:我只想更改列位置.

Note: I want to change only column positions.

推荐答案

如果empName是VARCHAR(50)列:

If empName is a VARCHAR(50) column:

ALTER TABLE Employees MODIFY COLUMN empName VARCHAR(50) AFTER department;

编辑

根据评论，您也可以执行以下操作:

Per the comments, you can also do this:

ALTER TABLE Employees CHANGE COLUMN empName empName VARCHAR(50) AFTER department;

请注意，重复empName是故意的.您必须告诉MySQL您想保持相同的列名.

Note that the repetition of empName is deliberate. You have to tell MySQL that you want to keep the same column name.

您应该注意，两种语法版本都特定于MySQL.例如，它们在PostgreSQL或许多其他DBMS中将无法使用.

You should be aware that both syntax versions are specific to MySQL. They won't work, for example, in PostgreSQL or many other DBMSs.

另一个正如@Luis Rossi在评论中指出的那样，您需要在AFTER修饰符之前完全指定更改后的列定义.上面的示例仅包含VARCHAR(50)，但是如果您需要其他特征(例如NOT NULL或默认值)，则还需要包括这些特征.有关更多信息，请参考 ALTER TABLE 上的文档.

Another edit: As pointed out by @Luis Rossi in a comment, you need to completely specify the altered column definition just before the AFTER modifier. The above examples just have VARCHAR(50), but if you need other characteristics (such as NOT NULL or a default value) you need to include those as well. Consult the docs on ALTER TABLE for more info.

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