5

私は人々がさまざまな場所の人々に投票を提出するデータベースを持っています。ある時点で、各場所で誰が最も多くの票を獲得したかを知りたいと思います。（人は2つの異なる場所で投票することができます）

これは私がこれまでに持っているSQLです：

SELECT placeId, userVotedId, cnt 
FROM 
    (SELECT uvo.userVotedId, p.placeId, count(*) as cnt 
     FROM users as u, users_votes as uvo, places as p 
     WHERE u.userId = uvo.userVotedId 
       AND p.placeId = uvo.placeId 
     GROUP BY userVotedId, placeId) 
AS RESULT

これは私にこの結果を与えます：

ここに画像の説明を入力してください

さて、これらは私が本当に欲しい行です：

ここに画像の説明を入力してください

これを取得できるように、クエリに何が欠けていますか？

  • 場所ごとに1つの結果が必要です。したがって、最も多くの票を獲得したuserVotedIdを使用して、個別のplaceIdのみを表示する必要があります。

  • 同点の場合は、ランダムな勝者が行います！

4

3 に答える 3

3

もう 1 つ集計が必要なようです。値にMAX()集計を使用し、次のようにします。cntGROUP BY placeId, userVotedId

SELECT placeId, userVotedId, max(cnt)
FROM 
(
  SELECT uvo.userVotedId, p.placeId, count(*) as cnt 
  FROM users as u
  INNER JOIN users_votes as uvo
    ON u.userId = uvo.userVotedId 
  INNER JOIN places as p 
    ON p.placeId = uvo.placeId 
  GROUP BY userVotedId, placeId
) AS RESULT
GROUP BY placeId, userVotedId

注:JOINテーブル間のコンマの代わりに構文を使用するようにクエリを変更しました。

編集、コメントに基づいて、次のように動作するはずです。

select total.uservotedid,
  total.placeid,
  total.cnt
from
(
  SELECT uvo.userVotedId, p.placeId, count(*) as cnt 
  FROM users as u
  INNER JOIN users_votes as uvo
    ON u.userId = uvo.userVotedId 
  INNER JOIN places as p 
    ON p.placeId = uvo.placeId 
  GROUP BY userVotedId, placeId
) total
inner join
(
  select max(cnt) Mx, placeid
  from
  (
    SELECT uvo.userVotedId, p.placeId, count(*) as cnt 
    FROM users as u
    INNER JOIN users_votes as uvo
      ON u.userId = uvo.userVotedId 
    INNER JOIN places as p 
      ON p.placeId = uvo.placeId 
    GROUP BY userVotedId, placeId
  ) mx
  group by placeid
) src
  on total.placeid = src.placeid
  and total.cnt = src.mx

デモで SQL Fiddle を参照してください

結果は次のとおりです。

| USERVOTEDID | PLACEID | CNT |
-------------------------------
|          65 |      11 |   1 |
|          67 |      13 |   1 |
|          67 |      25 |   1 |
|          67 |      51 |   2 |

編集＃2、同点の場合に乱数を返す場合は、ユーザー変数を使用できます。

select uservotedid,
  placeid, 
  cnt
from
(
  select total.uservotedid,
    total.placeid,
    total.cnt,
    @rownum := case when @prev = total.placeid then @rownum+1 else 1 end rownum,
    @prev := total.placeid pplaceid
  from
  (
    SELECT uvo.userVotedId, p.placeId, count(*) as cnt 
    FROM users as u
    INNER JOIN users_votes as uvo
      ON u.userId = uvo.userVotedId 
    INNER JOIN places as p 
      ON p.placeId = uvo.placeId 
    GROUP BY userVotedId, placeId
  ) total
  inner join
  (
    select max(cnt) Mx, placeid
    from
    (
      SELECT uvo.userVotedId, p.placeId, count(*) as cnt 
      FROM users as u
      INNER JOIN users_votes as uvo
        ON u.userId = uvo.userVotedId 
      INNER JOIN places as p 
        ON p.placeId = uvo.placeId 
      GROUP BY userVotedId, placeId
    ) mx
    group by placeid
  ) src
    on total.placeid = src.placeid
    and total.cnt = src.mx
  order by total.placeid, total.uservotedid
) src
where rownum = 1
order by placeid, uservotedid

デモで SQL Fiddle を参照してください

于 2013-01-25T00:36:00.940 に答える
1 
SELECT placeId, userVotedId, MAX(cnt)
    FROM (SELECT uvo.userVotedId, p.placeId, count(*) AS cnt 
          FROM users as u, users_votes as uvo, places as p 
          WHERE u.userId = uvo.userVotedId AND p.placeId = uvo.placeId 
          GROUP BY userVotedId, placeId) AS RESULT
    GROUP BY  placeId
于 2013-01-25T00:35:14.037 に答える
1

簡単にするために、クエリを Test と呼びました。

SELECT * 
FROM Test T JOIN (
SELECT t.placeId, Max(t.cnt) maxcnt
FROM Test t
GROUP BY t.placeId) T2 ON T.placeId = T2.placeId and T.cnt = T2.maxcnt

これがフィドルです。

ところで - テスト = :

SELECT uvo.userVotedId, p.placeId, count(*) as cnt 
  FROM users as u
  INNER JOIN users_votes as uvo
    ON u.userId = uvo.userVotedId 
  INNER JOIN places as p 
    ON p.placeId = uvo.placeId 
  GROUP BY userVotedId, placeId

幸運を。

-- 編集 -- リクエストに応じて、最終的なコードは次のとおりです。

SELECT * 
FROM (SELECT uvo.userVotedId, p.placeId, count(*) AS cnt 
          FROM users as u, users_votes as uvo, places as p 
          WHERE u.userId = uvo.userVotedId AND p.placeId = uvo.placeId 
          GROUP BY userVotedId, placeId) T JOIN (
SELECT t.placeId, Max(t.cnt) maxcnt
FROM (SELECT uvo.userVotedId, p.placeId, count(*) AS cnt 
          FROM users as u, users_votes as uvo, places as p 
          WHERE u.userId = uvo.userVotedId AND p.placeId = uvo.placeId 
          GROUP BY userVotedId, placeId) t
GROUP BY t.placeId) T2 ON T.placeId = T2.placeId and T.cnt = T2.maxcnt
于 2013-01-25T00:57:35.027 に答える