如何在SQL Server中篩選器值爲NULL時篩選條件上的記錄？

Question

我想在兩種情況下過濾SQL Server中的記錄。我正在爲此寫一個存儲過程。

這是我的查詢

// Parameters 
@carNo AS INT 
@carEngineNo AS INT = null // this is optional 

Select * 
From CarLog 
//Some Joins 
Where 
    CarLog.car_no = carNo 
    // here I want condition, I tried this but there is some syntax error 
    And CASE 
      When @carEngineNo IS NOT NULL THEN CarLog.engine_no= carEngineNo 
      WHEN @carEngineNo IS NULL THEN CarLog.engine_no = CarLog.engine_no 
      END 

我怎樣才能做到這一點？

Answer 1

很簡單OR

... 
AND (@carEngineNo is NULL or CarLog.engine_no = @carEngineNo) 

想到追加option(recompile)到您的查詢，因爲實際的參數設置可能會有所不同的。

---

您case固定：

AND CarLog.engine_no = 
     CASE 
     When @carEngineNo IS NOT NULL THEN @carEngineNo 
     WHEN @carEngineNo IS NULL THEN CarLog.engine_no 
     END 

備用：在關鍵字

AND CarLog.engine_no = IsNull(@carEngineNo, CarLog.engine_no) 

Answer 2

使用，

isnull(@carEngineNo,-1) in (-1, CarLog.engine_no) 

如果@carEngineNo爲null，則它得到的 - 1或否則我們得到那個。