如何更改超过 1 列的表列数据类型?

2021-11-27 00:00:00 mysql alter-table

例如:

ALTER TABLE webstore.Store MODIFY COLUMN (
  ShortName VARCHAR(100),
  UrlShort VARCHAR(100)
);

但是上面的方法不起作用.我正在使用 MySql 5.x

The above however does not work. I am using MySql 5.x

推荐答案

ALTER TABLE 可以在一条语句中进行多张表的更改，但是MODIFY COLUMN 一次只能对一列起作用，所以需要指定MODIFY COLUMN 用于您要更改的每一列:

ALTER TABLE can do multiple table alterations in one statement, but MODIFY COLUMN can only work on one column at a time, so you need to specify MODIFY COLUMN for each column you want to change:

ALTER TABLE webstore.Store MODIFY COLUMN ShortName VARCHAR(100), MODIFY COLUMN UrlShort VARCHAR(100);

另外，请注意手册中的警告:

Also, note this warning from the manual:

当您使用 CHANGE 或 MODIFY 时，column_definition 必须包括数据类型和应应用于新列的所有属性，除了 PRIMARY KEY 或 UNIQUE 等索引属性.原始定义中存在但未为新定义指定的属性不会被继承.

When you use CHANGE or MODIFY, column_definition must include the data type and all attributes that should apply to the new column, other than index attributes such as PRIMARY KEY or UNIQUE. Attributes present in the original definition but not specified for the new definition are not carried forward.

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