Question

任何人都可以帮我更有效地撰写此查询吗？

我有一个捕获TCP流量的表，我想更新一个名为RowNumForFlow的列，它简单地说就是该流中IP数据包的序列号。下面的代码工作正常，但速度很慢。

declare @FlowID int
declare @LastRowNumInFlow int
declare @counter1 int
set @counter1 = 0

while (@counter1 < 1)
BEGIN
set @counter1 = @counter1 + 1   

-- 1)
select  top 1
        @FlowID = t.FlowID
from    Traffic t 
where   t.RowNumInFlow is null

if (@FlowID is null)
    break

-- 2)
set @LastRowNumInFlow = null

select  top 1
        @LastRowNumInFlow = RowNumInFlow
from    Traffic 
where   FlowID=@FlowID and RowNumInFlow is not null
order by ID desc

if @LastRowNumInFlow is null
    set @LastRowNumInFlow = 1
else
    set @LastRowNumInFlow = @LastRowNumInFlow + 1

update Traffic set RowNumInFlow = @LastRowNumInFlow
where ID = (select top 1 ID from Traffic where 
            flowid = @FlowID and RowNumInFlow is null)


END

查询运行后的示例表值：

    
ID  FlowID  RowNumInFlow
448923  44  1
448924  44  2
448988  44  3
448989  44  4
448990  44  5
448991  44  6
448992  44  7
448993  44  8
448995  44  9
448996  44  10
449065  44  11
449063  45  1
449170  45  2
449171  45  3
449172  45  4
449187  45  5

Answer 1

这样的事情：

update
    T
set
    RowNumInFlow = @TheNumber
FROM
   (
    SELECT
       ID, 
       ROW_NUMBER() OVER (PARTITION BY FlowID ORDER BY ID) AS TheNumber
    FROM
       Traffic
   ) T

评论后：

update
    T1
set
    RowNumInFlow = TR.TheNumber
FROM
   Traffic T1
   JOIN 
   (
    SELECT
       ID, 
       ROW_NUMBER() OVER (PARTITION BY FlowID ORDER BY ID) AS TheNumber
    FROM
       Traffic
   ) TR ON T1.ID = TR.ID
   WHERE
       T1.RowNumInFlow IS NULL --like this?

查询以更新rowNum

1 个答案: