Question

我有一个相对简单的存储过程，但是事务表中的数据量导致它永远运行。任何关于我可以优化查询或将其转换为不使用游标的方式的建议将非常感激。

BEGIN
-- SET NOCOUNT ON added to prevent extra result sets from
-- interfering with SELECT statements.
SET NOCOUNT ON;

DECLARE @ItemID uniqueidentifier 

SET @CurrentCount = 0;

DECLARE @TempTransTable TABLE
(
    ID uniqueidentifier
)

-- Insert statements for procedure here
DECLARE curs_GetAllItems CURSOR LOCAL STATIC FORWARD_ONLY READ_ONLY FOR
    select 
        ID
    from 
        item
    where 
        locationid in 
            (
                -- gets corona locations
                select 
                    Locations.ID
                from Locations
                    left outer join unit
                        on unit.locationid = locations.id
                where unit.unittype = '4'
            )
        and stat not in (1,10,11,13) -- only items not in stock

    OPEN curs_GetAllItems

    FETCH NEXT FROM curs_GetAllItems INTO @ItemID
        WHILE (@@FETCH_STATUS =0)
        BEGIN
            -- Clear table to ensure accurate data
            DELETE FROM @TempTransTable

            -- Insert transaction records to delete
            -- Every transaction except the first two and the last
            INSERT INTO @TempTransTable
            select 
                ID 
            from 
                transactions 
            where 
                transactions.id not in
                    (select ID from (select top 2 * from transactions where itemid = @ItemID order by transdate asc) as t1
                    union 
                    select ID from (select top 1 * from transactions where itemid = @ItemID order by transdate desc) as t2)
                and itemid = @ItemID

            -- Delete trans records
            DELETE FROM 
                dbo.transactions 
            WHERE 
                transactions.ID in (select ID from @TempTransTable);

        -- Get next item.id
        FETCH NEXT FROM curs_GetAllItems INTO @ItemID
        END
    CLOSE curs_GetAllItems
    DEALLOCATE curs_GetAllItems
END

Answer 1

;with tmp as (
    select *,
           rn_asc = ROW_NUMBER() over (partition by t.itemid order by transdate asc),
           rn_desc = ROW_NUMBER() over (partition by t.itemid order by transdate desc)
      from transactions t
     where exists (
          select *
          from item i
          join Locations l on i.locationid = l.ID
          join unit u on u.locationid = l.id and u.unittype = '4'
         where i.id = t.itemid)
       and stat not in (1,10,11,13) -- only items not in stock
)
    delete tmp
     where rn_asc > 2 and rn_desc > 1;

Answer 2

我认为您应该检查一下您的方法。应该可以在没有光标和循环的情况下进行管理。可能是您需要使用中间临时表（考虑为其添加索引）。

其他观点：如果这些查询很难并且他们在数据库中进行并发更改，则可以轻松解决问题 - 锁定，超时和不一致的数据。

SQL - 慢速光标简单存储过程

2 个答案: