通过减去值来更新列 [英] update a column by subtracting a value

问题描述

我正试图提出一个将更新points的MySQL查询...我可以做这样的事情吗?

I'm trying to come up with a MySQL query that will update points... Can I do something like this?

UPDATE `a75ting`.`username` SET `points` = '`points` - 5'

推荐答案

UPDATE a75ting.username
SET points = points - 5

通过将单引号放在点-5"周围，可以将该表达式转换为纯文本字符串.不用引号就可以使MySQL看到您正在引用一个字段(点)，并从其当前值中减去5.

by putting the single quotes around the "points -5", you converted that expression into a plaintext string. Leaving it without the quotes lets MySQL see you're referring to a field (points) and subtracting 5 from its current value.

这篇关于通过减去值来更新列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IT屋！