使用 if 条件更新 MySQL
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时间：2020-08-31 16:38:50 来源:igfitidea点击:
Update MySQL with if condition
提问by Martina
It seems I have big problems with conditional queries.
看来我对条件查询有很大的问题。
I have to do a conditional update. I write here what I would like to do:
我必须做一个有条件的更新。我在这里写我想做的事情：
IF(SELECT tipo FROM abbonamento WHERE idU = 17) = 'punti' THEN
UDPATE abbonamento SET punti = punti - 1
ELSE
UPDATE abbonamento SET bonus = bonus - 1
Obviously this doesn't work.
Any idea?
显然这行不通。
任何的想法？
回答by John Woo
MySQLsupports IFstatement.
MySQL支持IF声明。
UPDATE abbonamento
SET punti = IF(tipo = 'punti', punti - 1, punti),
bonus = IF(tipo <> 'punti', bonus - 1, bonus)
WHERE id = 17
or you can also use CASE
或者你也可以使用 CASE
UPDATE abbonamento
SET punti = CASE WHEN tipo = 'punti' THEN punti - 1 ELSE punti END,
bonus = CASE WHEN tipo <> 'punti' THEN bonus - 1 ELSE bonus END
WHERE id = 17
