user196572's questions

DECLARE @SubDesc1 nvarchar(100)   
SET @SubDesc1 = null

我想做这样的事情。

查询 1

SELECT * 
From Table1   
where Category = 'Category1'   
  AND [Description] ='ABC'   
  AND SubDescription1 IS NULL   
   OR SubDescription1 = @SubDesc1

查询 2

SELECT * 
FROM Table1   
WHERE Category = 'Category1'   
  AND [Description] ='ABC'  
  AND SubDescription1 = (Case WHEN @SubDesc1 IS NOT NULL 
                              Then @SubDesc1
                              ELSE SubDescription1 
                              END)

如果我的，他们都没有解决@SubDesc1 = 'def'

但是，它会让我记录在哪里SubDescription1 Is null和SubDescription1 = 'def'

我怎样才能做到这一点？