不要在SQL Server中盲目地追求一句处理 （3）

DECLARE @a int

SET @a = 1

 

DECLARE @t TABLE(

    id int IDENTITY,

    a int, b int)

DECLARE @dt datetime, @loop int, @id int

SET @loop = 0

WHILE @loop < 5

BEGIN

    SET @loop = @loop + 1

    RAISERROR('test %d', 10, 1, @loop) WITH NOWAIT

    SET @dt = GETDATE()

        SELECT [ITEM] FROM A

        WHERE @a = 0

            AND [ITEM] < 'A'

        UNION ALL

        SELECT [ItemNumber] FROM B

        WHERE @a = 1

            AND [ItemNumber] < 'A'

    INSERT @t(a) VALUES(DATEDIFF(ms, @dt, GETDATE()))

    SELECT @id = SCOPE_IDENTITY(), @dt = GETDATE()

        IF @a = 0

            SELECT [ITEM] FROM A

            WHERE [ITEM] < 'A'

        ELSE IF @a = 1

            SELECT [ItemNumber] FROM B

            WHERE [ItemNumber] < 'A'

    UPDATE @t SET b = DATEDIFF(ms, @dt, GETDATE())

    WHERE id = @id

END

SELECT * FROM @t

UNION ALL

SELECT NULL, SUM(a), SUM(b) FROM @t