MYSQL的update的高级用法

MYSQL的update

多个表的UPDATE操作, 指定联合条件where
UPDATE items,month SET items.price=month.price WHERE items.id=month.id;
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注意：多表 UPDATE 不可以使用 ORDER BY 或 LIMIT

链接更新,,在需要中间表的时候
-- 更新一张表
UPDATE table1 t1 
INNER JOIN table2 t2 
ON t1.t2_id = t2.t1_id 
SET t1.price = t2.price * 0.8,
t2.update_date = NEW ()
-- 同时更新两张表
UPDATE product p 
INNER JOIN productPrice pp 
ON p.productId = pp.productId 
SET pp.price = pp.price * 0.8, 
p.dateUpdate = CURDATE() 
WHERE p.dateCreated < '2004-01-01' 

--plus:
update xcs_user_credit_score a1,xcs_user_credit_score a2
set a1.user_currday_score=(case when a1.user_currday_score+10<0 then a1.user_currday_score+10 else 0 end)
where a1.pt_day='2017-09-20' and a2.pt_day='2017-09-19'
and a1.uid=a2.uid
and (a1.seqing_score=0 and a1.user_silent_score=0 and a1.jubao_score=0 and a1.chengpaopao_score=0 and a1.weifan_score=0)
and a1.user_currday_score<0
;