Question

我是一个非常初学的sql，我需要编写一个SP，以增加产品的视图数量。当用户在网站上搜索时，我们希望增加搜索返回的所有产品的计数器。我发现我的SP存在两个问题：

它使用光标
它启动了很多交易

许多线程同时调用SP。实现之后，我遇到了很多超时异常。我的计数表看起来像这样：

ProductsViewsCount（ProductId int，Timestamp datetime，ViewType int，Count int）

Tiemstamp列四舍五入到调用SP的.net代码中最接近的小时。基本上我会按小时计算观点。

SP看起来像这样：

    CREATE PROCEDURE [dbo].[IncrementProductsViews]
    -- Add the parameters for the stored procedure here
    @ProductsIds as varchar(max) = '', --CSV ids of products that were returned by search
    @ViewType int,
    @Timestamp datetime
AS
BEGIN
    -- SET NOCOUNT ON added to prevent extra result sets from
    -- interfering with SELECT statements.
    SET NOCOUNT ON;

    DECLARE @id int 
    DECLARE idsCursor CURSOR FOR 
        SELECT Data FROM dbo.Split(@ProductsIds,',')

    OPEN idsCursor
    FETCH NEXT FROM idsCursor INTO @id
    WHILE @@FETCH_STATUS = 0
    BEGIN
        BEGIN TRAN
            UPDATE dbo.ProductsViewsCount SET Count = Count + 1 
                WHERE ProductId = @id AND ViewType = @ViewType AND Timestamp = @Timestamp
            if @@rowcount = 0
            BEGIN
                INSERT INTO dbo.ProductsViewsCount (ProductId, Timestamp, ViewType, Count) 
                    VALUES (@id, @Timestamp, @ViewType, 1)
            END
        COMMIT TRAN     
        FETCH NEXT FROM idsCursor INTO @id
    END     
    CLOSE idsCursor   
    DEALLOCATE idsCursor
    select 1
END

我能以更有效的方式做到这一点吗？

Answer 1

您可以在设置操作而不是光标上执行此操作：

CREATE PROCEDURE [dbo].[IncrementProductsViews]
    -- Add the parameters for the stored procedure here
    @ProductsIds as varchar(max) = '', --CSV ids of products that were returned by search
    @ViewType int,
    @Timestamp datetime
AS
BEGIN
    -- SET NOCOUNT ON added to prevent extra result sets from
    -- interfering with SELECT statements.
    SET NOCOUNT ON;

    ;WITH CTE AS
    (
        SELECT *
        FROM dbo.ProductsViewsCount
        WHERE ViewType = @ViewType AND [Timestamp] = @Timestamp
    )


    MERGE CTE AS A
    USING (SELECT * FROM dbo.Split(@ProductsIds,',')) B
    ON A.ProductId = B.Data 
    WHEN MATCHED THEN UPDATE SET A.[Count] = B.[Count] + 1
    WHEN NOT MATCHED BY TARGET THEN
    INSERT(ProductId, [Timestamp], ViewType, [Count])
    VALUES(Data, @Timestamp, @ViewType, 1);

    SELECT 1 -- I don't know why this is here
END

Answer 2

使用SQL Server 2008，您有一个不错的新选项（http://technet.microsoft.com/en-us/library/bb510625（SQL.100）.aspx）：

with ProductViewsCountSelect as (select * from ProductViewsCount where ViewType = @ViewType and [Timestamp] = @Timestamp)
merge into ProductViewsCountSelect
    using (select data, count(*) as cnt from dbo.split('A,B,C,A', ',') group by data) d on ProductViewsCountSelect.ProductId = d.data
    when matched   
        then update set ProductViewsCountSelect.Count = ProductViewsCountSelect.count + cnt
    when not matched 
         then insert (ProductId, [TimeStamp], ViewType, [Count]) values( d.data, @TimeStamp, @ViewType, cnt);

T-SQL：存储过程增加产品视图计数

2 个答案: