MySQL在where後面使用case when
阿新 • • 發佈:2018-11-15
在MySQL中,在where後面使用case when的說明
報錯語句
select *
from A, B
where B.name in
CASE
when A.id = 0 then ('aaa', 'bbb')
when A.id = 1 then ('bbb', 'ccc')
when A.id = 2 then ('ccc', 'ddd')
END
正確寫法:將B.name in 放到CASE END 中
select *
from A, B
where
CASE
when A.id = 0 then B.name in ('aaa', 'bbb')
when A.id = 1 then B.name in ('bbb', 'ccc')
when A.id = 2 then B.name in ('ccc', 'ddd')
END
補充:當使用 B.name = 時,將不會出現以上問題,也就是如下寫法也正確
select *
from A, B
where B.name =
CASE
when A.id = 0 then 'aaa'
when A.id = 1 then 'bbb'
when A.id = 2 then 'ccc'
END