Question

Hey guys I m trying to set up a quick math table and figured I can save myself some time if I created a foreign key that was the negation of two of my columns. Probably a bad idea but I think it d be a neat hat trick.

So lets say I have a table set up like this

ID    |    A    |    B    |    C (Foreign?)
0     |    5    |    3    |   (2)

因此,这里的简单数是

A-B=C

我永远不需要不止一个字眼,但我会问,这时常通过麻省不断更新<代码>A或B。或获得<代码>A的数值 B & C,用于向终端用户展示。页: 1

ID    |    A    |    B
0     |    5    |    3

SELECT A, B, (A-B) AS C 
FROM `sometable`

But I figure this would be a lot of extra math on the server?

Answer 1

www.un.org/spanish/ecosoc 我认为,你应该在本表格上写上一个插头/更新的触发点,以介绍你试图实现的目标。

That makes more sense and creating a foreign key for that is extremely BAD PRACTICE!

请将此改为:

友情链接