MySql将值从一行复制到另一行 [英] MySql copy value from one row to another

问题描述

这应该是非常基本的，但我不知道.有一个表值"

This should be pretty basic but i can't figure it out. Have a table 'values'

entity|attribute|value

frank - shirt - red 
frank - hat   - green
sam   - shirt - blue
sam   - hat   - orange

我该如何将同一个人的所有帽子颜色设置为与衬衫颜色相同，以给坦率的红色帽子和sam蓝色的帽子.

how do i set all hats color's to be the same as the shirt color, of the same person to give frank a red hat and sam a blue hat.

推荐答案

我一直在寻找解决方案，因此我发表了这篇文章. 但是，运行sql会导致语法错误.

i was looking for a solution to this and i came up on this post. however running the sql lead to a syntax error.

参考mysql文档 http://dev.mysql.com/doc/refman/5.0/en/update.html 我注意到-至少在版本5中-mysql为此使用了不同的语法.

Refering to the mysql docs http://dev.mysql.com/doc/refman/5.0/en/update.html i noticed - at least in version 5 - mysql has a different syntax for this.

一般声明为:

update table t1, table t2 
set t1.field1 = t2.field2, ..., t1.fieldN = t2.fieldN
where t1.someid = t2.someid and t1.fieldX = '...' and t2.fieldY = '...'

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