具有最大行數的聚合SQL查詢要考慮

我有投票的數據與team_id，ip_address和date_voted字段的表，我需要返回票的數量每個team_id但只能算在24小時內每個IP地址的前10行。

2010-02-24 David

沒有時間檢查，但以下應該做的伎倆。

SELECT Yr, DoY, team_id, SUM(IF NbVote < 10, NbVote, 10) As FilteredVoteCount 
FROM (
    SELECT YEAR(date_voted) AS Yr, DAYOFYEAR(date_voted) AS DoY, 
    team_id, 
    ip_address, 
    COUNT(*) AS NbVotes 
    FROM myTable 
    -- WHERE here for some possible extra condition. 
    GROUP BY YEAR(date_voted), DAYOFYEAR(date_voted), team_id, ip_address 
) 
GROUP BY Yr, DoY, team_id 
ORDER BY Yr, DoY, team_id -- or some other order may be desired.

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2010-02-24 18:52:32 mjv

在子選擇中放置「DISTINCT」語句和「ORDER BY」子句應該使該解決方案有效。 – Sonny

對不起mjv，我當然應該更具體。我需要表中存在的每24小時的總計數。因此，例如，我需要每行的總數，每個ip地址每天最多10行，例如星期一，星期二，星期三等等。確實有意義或者我是揮霍無度的只對自己有意義？ :) – David

@David，看看我的編輯（除了增加每天計算總數的支持外，我還添加了我最初忘記的GROUP BY ......）。如果你對某一天的日子感興趣，而不是單日那天，只需通過DAYOFWEEK（date_voted）改變'YEAR（date_voted），DAYOFYEAR（date_voted）' – mjv

假設：只有前十票的隊伍（在投票表中每一行是TEAM_ID投票）從給定的IP地址應該給定日期計算。

所以這裏是每團隊每天的原始投票。

select team_id, vote_date, ip_address, count(*) as raw_vote_count 
    from votes 
group by team_id, vote_date, ip_address

現在，使用，糾正投票下來的不超過十號與CASE表達式：

select team_id, vote_date, ip_address, 
     case when raw_vote_count > 10 
      then 10 
      else raw_vote_count 
     end as adjusted_vote_count 
    from (select team_id, vote_date, ip_address, count(*) as raw_vote_count 
      from votes 
     group by team_id, vote_date, ip_address 
     ) sub1

如果再要通過一天總票數，它的：

select team_id, sum(adjusted_vote_count) 
    from (
     select team_id, vote_date, ip_address, 
       case when raw_vote_count > 10 
        then 10 
        else raw_vote_count 
       end as adjusted_vote_count 
     from (select team_id, vote_date, ip_address, count(*) as raw_vote_count 
       from votes 
       group by team_id, vote_date, ip_address 
      ) sub1 
     ) 
where date = :mydate 
group by team_id 
order by team_id

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2010-02-24 20:23:14

具有最大行數的聚合SQL查詢要考慮

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