Question

我有以下存储过程，我想让它更有效率。当p_training不为null时，我会得到更多记录。

ALTER PROCEDURE [dbo].GetAssets
    @p_language VARVHAR(1) = 'E',
    @p_training BIT = NULL

AS
  IF (@p_training IS NOT NULL)
    SELECT Asset_Key AS CodeId,
           CASE WHEN @p_language = 'E' THEN HRMS_Desc_Eng
                WHEN @p_language = 'F' THEN HRMS_Desc_Fre
           END AS CodeName
    FROM Assets
    WHERE Asset_Type NOT IN ('C')
    ORDER BY CodeName
  ELSE
    SELECT Asset_Key AS CodeId,
           CASE WHEN @p_language = 'E' THEN HRMS_Desc_Eng
                WHEN @p_language = 'F' THEN HRMS_Desc_Fre
           END AS CodeName
    FROM Assets
    WHERE Asset_Type NOT IN ('C')
    AND (LocationId < 2000 OR LocationId > 2030)
    ORDER BY CodeName

如何才能提高效率或删除if语句？

感谢您的建议。

Answer 1

如果真正关注性能，最好的方法是将原始Stored Procedure拆分为2：

第一个SP：

CREATE PROCEDURE GetAssetsNotNull
@p_language VARVHAR(1) = 'E'

AS
SELECT Asset_Key AS CodeId,
       CASE WHEN @p_language = 'E' THEN HRMS_Desc_Eng
            WHEN @p_language = 'F' THEN HRMS_Desc_Fre
       END AS CodeName
FROM Assets
WHERE Asset_Type NOT IN ('C')
ORDER BY CodeName

第二个SP：

CREATE PROCEDURE GetAssetsNull
@p_language VARVHAR(1) = 'E'
AS
SELECT Asset_Key AS CodeId,
       CASE WHEN @p_language = 'E' THEN HRMS_Desc_Eng
            WHEN @p_language = 'F' THEN HRMS_Desc_Fre
       END AS CodeName
FROM Assets
WHERE Asset_Type NOT IN ('C')
AND (LocationId < 2000 OR LocationId > 2030)
ORDER BY CodeName

最后，您只能根据参数调用SP：

IF @p_training IS NOT NULL
EXEC GetAssetsNotNull
ELSE
EXEC GetAssetsNull

编辑：最后一部分可以在应用程序端或SP本身完成。

Answer 2

我认为可以通过检查where子句中@p_training是否为空而不是使用IF

来减少代码重复

ALTER PROCEDURE [dbo].GetAssets
    @p_language VARVHAR(1) = 'E',
    @p_training BIT NULL    
AS
    SELECT Asset_Key AS CodeId,
           CASE WHEN @p_language = 'E' THEN HRMS_Desc_Eng
                WHEN @p_language = 'F' THEN HRMS_Desc_Fre
           END AS CodeName
    FROM Assets
    WHERE Asset_Type NOT IN ('C')
    AND (LocationId < 2000 OR LocationId > 2030 OR @p_training IS NOT NULL)
    ORDER BY CodeName

但这不会使查询更有效率。

根据参数制作更高效的SP

2 个答案: