select case

 

首先让我们看一下 CASE 的语法。在一般的 SELECT 中，其语法如下：

SELECT <myColumnSpec> =
CASE
WHEN <A> THEN <somethingA>
WHEN <B> THEN <somethingB>
ELSE <somethingE>
END 

 

SELECT h.ID, h.funtionID, h.userID, f.vc_Name AS funtionName,h.vc_Memo,
  (case   
   when h.KeyFlags='' then h.HookKey 
   when h.KeyFlags IS NULL then h.HookKey 
   else h.KeyFlags +'+'+ h.HookKey 
   end) as vHotKey  
FROM dbo.m_HotKeys h LEFT OUTER JOIN
      dbo.m_FuntionList f ON h.ID = f.ID AND f.i_Flag = 0
WHERE (h.i_Flag = 0)