我想检查子查询的值如何检查呢？

Question

这是我在 mysql

中的更新查询

UPDATE userentries
SET User_Rank = 
(
  SELECT 
  urc.rankofentr as User_Rank
  from UserRankingsys as urc 
  WHERE urc.entryid = userentries.id
  LIMIT 1
) 
where userentries.id = 15

我想检查该部分返回的值

(
  SELECT 
  urc.rankofentr as User_Rank
  from UserRankingsys as urc 
  WHERE urc.entryid = userentries.id
  LIMIT 1
)

如果此子查询 returns 大于 20，我要设置值 102

，我该怎么做

Answer 1

你可以使用 CASE

  SELECT case urc.rankofentr when > 20 then 20 
                             else urc.rankofentr
         end as User_Rank
  from UserRankingsys as urc 
  WHERE urc.entryid = userentries.id
  LIMIT 1

给你sql

UPDATE userentries
SET User_Rank = 
(
 SELECT case urc.rankofentr when > 20 then 20 
                             else urc.rankofentr
         end as User_Rank
  from UserRankingsys as urc 
  WHERE urc.entryid = userentries.id
  LIMIT 1
) 
where userentries.id = 15;

我想检查子查询的值如何检查呢？

I want to check the value of subquery how to check it?

mysql

subquery