Question

我需要将此c＃行转换为SQL查询：

from t in table where type == 0 ? t.colA=1 : t.ColB=1

我尝试过

select * from table t where
BEGIN IF @type=0 THEN t.colA=1 END
BEGIN IF @type=1 THEN t.colB=1 END

但我明白了

Incorrect syntax near the keyword 'BEGIN'.

和

Incorrect syntax near the keyword 'THEN'.

我在做什么错？甚至有可能作为SQL命令来执行此操作？

Answer 1

只需使用布尔表达式：

select *
from table t
where (@type = 0 and t.colA = 1) or
      (@type = 1 and t.colB = 1)

如果您想要@type不为0或1时的所有内容，请添加：

select *
from table t
where (@type = 0 and t.colA = 1) or
      (@type = 1 and t.colB = 1) or
      (@type not in (0, 1))  -- adjust if @type could be NULL

Answer 2

您可以使用CASE：

select * from table t
where (CASE @type  WHEN 0 THEN colA
                   WHEN 1 THEN colB
       END) = 1

Answer 3

CASE是TSQL中的“ if”函数

https://docs.microsoft.com/en-us/sql/t-sql/language-elements/case-transact-sql?view=sql-server-2017

TSQL如果在其他地方

3 个答案: