MySQL:如果列不存在，如何添加?

MySQL: How to add a column if it doesn#39;t already exist?(MySQL:如果列不存在，如何添加?)

问题描述

我想向表中添加一列，但如果它已经添加到表中，我不希望它失败.我怎样才能做到这一点?

I want to add a column to a table, but I don't want it to fail if it has already been added to the table. How can I achieve this?

# Add column fails if it already exists 
ALTER TABLE `TableName` ADD `ColumnName` int(1) NOT NULL default '0';

推荐答案

在存储过程中使用以下内容:

Use the following in a stored procedure:

IF NOT EXISTS( SELECT NULL
            FROM INFORMATION_SCHEMA.COLUMNS
           WHERE table_name = 'tablename'
             AND table_schema = 'db_name'
             AND column_name = 'columnname')  THEN

  ALTER TABLE `TableName` ADD `ColumnName` int(1) NOT NULL default '0';

END IF;

参考:

• INFORMATION_SCHEMA COLUMNS 表

这篇关于MySQL:如果列不存在，如何添加?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持编程学习网！