Question

我正试图在几行上执行“in”：

case when  (select distinct A from b ) in  ('test,'y') then 2

我收到错误：“子查询返回多行”。有没有办法使它有效？

编辑：

这个解决方案对我有用：

case when  exists (select  distinct a  from b
                        where a in  ('test','y')) then 2

谢谢大家。

Answer 1

select count(*) from b
where a in ('x','y')

Answer 2

保持概念相似：

CASE WHEN EXISTS (SELECT 1 FROM b WHERE a IN ('test', 'y')) THEN 2

如果IN b列中需要a个值，则

CASE WHEN (SELECT COUNT(DISTINCT a) FROM b WHERE a IN ('test','y'))=2 THEN 2

或者，如果您只是想在IN条件中返回不同值的数量，那么您就不需要CASE：

SELECT COUNT(DISTINCT a) FROM b WHERE a IN ('test','y')