如果那么在存储过程中循环

Question

我试图在存储过程中使用IF THEN循环,如下所示:

@A varchar(100),
@B varchar(100)  
AS
BEGIN 

IF (@A = 'NULL' AND @B = 'NULL')
    BEGIN
    SELECT TOP 5 X1, X2, A, B, Y1, Y2, X3
        FROM mytable
    ORDER BY Y1 DESC
    SELECT TOP 5 X1, X2, A, B, Y1, Y2, X3
    FROM mytable
    ORDER BY Y2 DESC
    END

ELSE IF (@A = 'NULL' AND @B IS NOT NULL) 
    BEGIN
    SELECT TOP 5 Y1Rank, X1, X2, A, B, Y1, Y2, X3
    FROM (
            SELECT *,
        ROW_NUMBER() OVER (PARTITION BY B ORDER BY Y1 DESC) AS 'Y1Rank'
        FROM mytable
        WHERE B = @B
        ) b1

    SELECT TOP 5 Y2Rank, X1, X2, A, B, Y1, Y2, X3
    FROM (
        SELECT *,
        ROW_NUMBER() OVER (PARTITION BY B ORDER BY Y2 DESC) AS 'Y2Rank'
        FROM mytable
        WHERE B = @B
        ) b2
    END

ELSE IF (@A IS NOT NULL AND @B = 'NULL')
    BEGIN
    SELECT TOP 5 Y1Rank, X1, X2, A, B, Y1, Y2, X3
    FROM (
        SELECT *,
        ROW_NUMBER() OVER (PARTITION BY A ORDER BY Y1 DESC) AS 'Y1Rank'
        FROM mytable
        WHERE A = @A
        ) b3

    SELECT TOP 5 Y2Rank, X1, X2, A, B, Y1, Y2, X3
    FROM (
        SELECT *,
        ROW_NUMBER() OVER (PARTITION BY A ORDER BY Y2 DESC) AS 'Y2Rank'
        FROM mytable
        WHERE A = @A
        ) b4
    END
ELSE
    BEGIN
    SELECT TOP 5 Y1Rank, X1, X2, A, B, Y1, Y2, X3
    FROM (
        SELECT *,
        ROW_NUMBER() OVER (PARTITION BY A, B ORDER BY Y1 DESC) AS 'Y1Rank'
        FROM mytable
        WHERE A = @A AND B = @B
        ) b5

    SELECT TOP 5 Y2Rank, X1, X2, A, B, Y1, Y2, X3
    FROM (
        SELECT *,
        ROW_NUMBER() OVER (PARTITION BY A, B ORDER BY Y2 DESC) AS 'Y2Rank'
        FROM mytable
        WHERE A = @A AND B = @B
        ) b6
    END
END
GO

我的目标是SP的工作方式与搜索引擎的功能类似:

1. 如果用户同时指定@A和@B(例如,@ A = alpha,@ B = bravo),则在Y1方面返回前5个结果,在Y2方面返回前5个结果.这些结果是A = alpha和B = bravo.
2. 如果用户仅指定@A(例如,@ A = alpha)或@B(@B = bravo)(另一个将输入为'NULL'),则按Y1和前5个结果返回前5个结果Y2.这些结果仅在A = alpha和任何B或B = bravo和任何A.
3. 如果用户没有指定A和B中的任何一个(两者都输入为"NULL"),则它以Y1的形式返回前5个结果,并且以Y2的形式返回前5个结果.那些结果'A和B可以是任何结果.

代码的实际结果证明:

• 如果我同时指定A和B,则代码可以正常工作.
• 如果我没有指定A或B(输入@A ='NULL'和@B ='NULL'),代码也可以正常工作.
• 但是,如果我只指定A和B中的一个(例如,输入@A ='alpha'和@B ='NULL';或输入A ='NULL'和B ='Bravo'),则代码仅返回一个空表与标题.

有没有人可以帮我这个？非常感谢.

================================================== ========================================= BTW,我尝试使用相同的代码查询但不是存储过程.我试过了

DECLARE @A varchar(100),
@B varchar(100)
SET @A = 'NULL' 
SET @B = 'Bravo'

和

DECLARE @A varchar(100),
@B varchar(100)
SET @A = 'Alpha' 
SET @B = 'NULL'   

然后跟着我在存储过程中使用的代码完全相同,它正是我想要的!我认为它们应该是等价的,但不知何故只能在普通查询中工作,而不能在存储过程中工作......我真的很困惑.

Answer 1

尝试使用参数的默认值，如下所示：

@A varchar(100) = 'NULL',
@B varchar(100) = 'NULL'

这样，如果用户仅提供一个参数的值，则另一个参数只需使用默认值。