0 
CREATE TABLE newsarticles
    (katernenID int, Buitenland int, Economie int, Sport int, Cultuur int, Wetenschap int, Media int, userID int);

INSERT INTO newsarticles
    (katernenID, Buitenland, Economie, Sport, Cultuur, Wetenschap, Media, userID)
VALUES
    (1, 24, 5, 52, 3, 2, 3, 1),
    (3, 2, 0, 0, 1, 51, 66, 5),
    (4, 50, 2, 67, 41, 1, 54, 6),
    (5, 30, 1, 79, 0, 0, 12, 7),
    (6, 9, 26, 0, 100, 11, 0, 8),
    (7, 2, 14, 8, 1, 33, 98, 9),
    (8, 0, 1, 0, 1, 0, 0, 10);



SELECT
  userID,GROUP_CONCAT(amt ORDER BY amt DESC) AS four_highest
FROM
(
  SELECT userID, @rownum := @rownum + 1 AS rank, NAME, amt FROM (
    SELECT userID, Buitenland AS amt, 'Buitenland' AS NAME UNION
    SELECT userID, Economie, 'Economie'  UNION
    SELECT userID, Sport, 'Sport' UNION
    SELECT userID, Cultuur, 'Cultuur'  UNION
    SELECT userID, Wetenschap, 'Wetenschap'  UNION
    SELECT userID, Media, 'Media' 
         FROM( SELECT katernenID, Buitenland, Economie, Sport, Cultuur, Wetenschap, Media, userID FROM newsarticles  ) temp

  ) amounts, (SELECT @rownum := 0) r
) top4
GROUP BY userid

上記のクエリのように UNION を作成したいのですが、Union が機能しません。UNION には FROM ステートメントがすぐに必要です。お気に入り：

    SELECT userID, Wetenschap, 'Wetenschap'  
                 FROM( SELECT katernenID, Buitenland, Economie, Sport, Cultuur, Wetenschap, Media, userID FROM newsarticles  ) temp
                 UNION
    SELECT userID, Media, 'Media' 
         FROM( SELECT katernenID, Buitenland, Economie, Sport, Cultuur, Wetenschap, Media, userID FROM newsarticles  ) temp

しかし、FROM ステートメントを繰り返すことはできません。サブクエリの計算が多すぎます。これを行う方法はありますか、それとも何か不足していますか?

また

max(a_percentage,b_percentage,c_percentage),SecondMAX(a_percentage,b_percentage,c_percentage),ThirdMAX(a_percentage,b_percentage,c_percentage)の新しい列が欲しい

    SELECT id,a,b,c,a_percentage,b_percentage,c_percentage
    -- -------------------------max percentage
    GREATEST(axis_per, hdfc_per,icici_per,citi_per ) AS max_per,
    FROM (
      SELECT id,a,b,c,
      IFNULL(a*100/a+b+c+d,0) AS a_percentage,
      IFNULL(b*100/a+b+c+d,0) AS b_percentage,
      IFNULL(c*100/a+b+c+d,0) AS c_percentage
      FROM test
        WHERE TIME > '2012-01-01'
        GROUP BY id
      ) A
4

1 に答える 1

0

私があなたを正しく理解していれば、でテーブル名だけを使用し、FROM各行の列に次のようなエイリアスを付けることができるはずです。

SELECT
  userID,GROUP_CONCAT(amt ORDER BY amt DESC) AS four_highest
FROM
(
  SELECT userID, @rownum := @rownum + 1 AS rank, NAME, amt FROM (
    SELECT userID, Buitenland AS amt, 'Buitenland' AS NAME FROM newsarticles NAME UNION
    SELECT userID, Economie, 'Economie'  FROM newsarticles UNION
    SELECT userID, Sport, 'Sport'  FROM newsarticles UNION
    SELECT userID, Cultuur, 'Cultuur'  FROM newsarticles UNION
    SELECT userID, Wetenschap, 'Wetenschap'  FROM newsarticles UNION
    SELECT userID, Media, 'Media' FROM newsarticles
) amounts, (SELECT @rownum := 0) r
) top4
GROUP BY userid
于 2012-11-09T15:28:07.590 に答える