case when.then.else.endSQL实现如下功能用case when...then...else.end 实现当A=1时,那么B=1,否则B=0;C=0,否则C=1

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casewhen.then.else.endSQL实现如下功能用casewhen...then...else.end实现当A=1时,那么B=1,否则B=0;C=0,否则C=1casewhen.then

case when.then.else.endSQL实现如下功能用case when...then...else.end 实现当A=1时,那么B=1,否则B=0;C=0,否则C=1
case when.then.else.end
SQL实现如下功能
用case when...then...else.end 实现
当A=1时,那么B=1,否则B=0;C=0,否则C=1

case when.then.else.endSQL实现如下功能用case when...then...else.end 实现当A=1时,那么B=1,否则B=0;C=0,否则C=1
首先你要搞清楚case when的用法
case when最终得到的结果是一个值,而不是多个值,更不是赋值.你写的就是赋值了.
你是要更新么?
update 表 set b = (case A when 1 then 1 else 0 end),c = (case A when 1 then 0 else 1 end)
一定要写两次才行.
如果查询语句,那么B和C应该是你构建的两个列了
select (case A when 1 then 1 else 0 end) as B,
(case A when 1 then 0 else 1 end) as C
from 表
case when也可以写成
case when A = 1 then 1 else 0 end这样的形式.
不管怎么写,你要记住,case when语句,得到的是一个值,而不是在里面赋值.
因为你写的并不明确,所以大家都搞不清楚你到底是要更新B列和C列还是要查询

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