sql - 在 WHERE 条件下加倍

Question

是否可以在 where 语句 @Age 中执行类似这里发生的事情？参数？

 @AGE Varchar(8)

 SELECT NAME FROM TABLE WHERE 
 (
 If @AGE='man'
  then (AGE = 'man' or AGE = 'boy')
  else (AGE = 'man')
 )
 AND City IS NULL

Answer 1

是的，像这样:

SELECT NAME FROM TABLE WHERE 
((@AGE='man'
   AND (AGE = 'man' or AGE = 'boy'))
OR
(@AGE <> 'man'
  AND (AGE = 'man')))
AND City IS NULL

注意条件 @AGE <> 'man'可能需要根据@AGE 变量是否可以为空进行调整。

我回答了一个非常相似的问题 here .

This is a very common technique in a WHERE clause. If you want to apply some "IF" logic in the WHERE clause all you need to do is add the extra condition with an boolean AND to the section where it needs to be applied.