Alter SQL表-允许NULL列值 [英] Alter SQL table - allow NULL column value

问题描述

最初，表"MyTable"的定义如下:

Initially, the table "MyTable" has been defined in the following way:

CREATE TABLE IF NOT EXISTS `MyTable` (
  `Col1` smallint(6) NOT NULL AUTO_INCREMENT,
  `Col2` smallint(6) DEFAULT NULL,
  `Col3` varchar(20) NOT NULL,
);

如何以允许"Col 3"列为NULL的方式更新它?

How to update it in such a way that the column "Col 3" would be allowed to be NULL?

推荐答案

以下MySQL语句应修改您的列以接受NULL.

The following MySQL statement should modify your column to accept NULLs.

ALTER TABLE `MyTable`
ALTER COLUMN `Col3` varchar(20) DEFAULT NULL

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