在mysql中将正值更新为负值

Question

我有付款表字段

更新原因和金额以及总计字段更改为负数

UPDATE payment 
SET reason = 'refund' 
WHERE uid =5 AND date = '2012-05-01' AND accid =2 

更新单个查询是否可能？

Answer 1

如果我理解正确,您还需要将amount列设置为正值以及上述语句.

你可以使用这样的东西

UPDATE payment 
SET reason = 'refund', amount = amount * -1, total = total * -1
WHERE uid =5 AND date = '2012-05-01' AND accid =2

Answer 2

使用ABS(amount)，如果你想始终获得正整数。

SELECT ABS(5);

将输出5

SELECT ABS(-5);  

也会输出5