GROUP BY和最大的两列

Question

我有这些列的表：

id | series_id | season_id | episode_id | title | type ... 

我想获得具有独特series_id其中season_id和episode_id是最大行数。

Answer 1

一种解决方案是要做到这一点：

SELECT t1.* 
FROM YourTable AS t1 
INNER JOIN 
(
    SELECT 
    series_id, 
    MAX(season_id) AS MAxSeasonId, 
    MAX(Episode_id) AS MAXEpisodeID 
    FROM yourTable 
    GROUP BY series_id 
) AS t2 ON t1.series_id = t2.series_id 
     AND t1.season_id = t2.MaxSeasonId 
     AND t1.episode_id = t2.MaxEpisode_id; 

Answer 2

SELECT * 
FROM TableName t1 
WHERE EXISTS (
       SELECT 1 
       FROM t2 
       WHERE t1.series_id = t2.series_id 
       HAVING MAX(t2.season_id) = t1.season_id 
       AND MAX(t2.episode_id) = t1.episode_id 
      ) 

Answer 3

试试这个..

SELECT * FROM TABLE 
HAVING MAX(season_id) AND MAX(episode_id) 
GROUP BY series_id 

:)

Answer 4

我想这可能是矫枉过正，但它是唯一我发现这种方式对我很有用。

DECLARE @SeriesInfo TABLE 
(
    id   INT, 
    series_id INT, 
    season_id INT, 
    episode_id INT, 
    title  VARCHAR(50), 
    type  CHAR(1) 
); 
INSERT INTO @SeriesInfo VALUES (1, 1, 1, 1, 'Series 1 Season 1 Episode 1', 'A'), 
           (2, 1, 1, 2, 'Series 1 Season 1 Episode 2', 'A'), 
           (3, 1, 1, 3, 'Series 1 Season 1 Episode 3', 'A'), 
           (4, 1, 2, 1, 'Series 1 Season 2 Episode 1', 'A'), 
           (5, 1, 2, 2, 'Series 1 Season 2 Episode 2', 'A'), 
           (6, 2, 1, 1, 'Series 2 Season 1 Episode 1', 'A'), 
           (7, 2, 1, 2, 'Series 2 Season 1 Episode 2', 'A'), 
           (8, 2, 1, 3, 'Series 2 Season 1 Episode 3', 'A'), 
           (9, 2, 1, 4, 'Series 2 Season 1 Episode 4', 'A'), 
           (10, 2, 2, 1, 'Series 2 Season 2 Episode 1', 'A'), 
           (11, 2, 2, 2, 'Series 2 Season 2 Episode 2', 'A'), 
           (12, 2, 2, 3, 'Series 2 Season 2 Episode 3', 'A'); 
SELECT id, 
     series_id, 
     season_id, 
     episode_id, 
     title, 
     type 
FROM (
     SELECT ROW_NUMBER() OVER(PARTITION BY series_id ORDER BY season_id DESC, episode_id DESC) RowNum, 
       * 
     FROM @SeriesInfo 
     ) X 
WHERE X.RowNum = 1; 

--SELECT ROW_NUMBER() OVER(PARTITION BY series_id ORDER BY season_id DESC, episode_id DESC) RowNum, * FROM @SeriesInfo; 

（对不起，样本数据的满丰）

的一点是，如果我们只取series_id和season_id的最大值，我们不会得到任何一系列有效的对。在这两种情况下，第1季比第2季都多。 ROW_NUMBER（）子句将每行返回一个唯一的数字，但由于“PARTITION BY”，它会为每个series_id重新启动（请参阅注释掉的行） 。如果我们仅返回ROW_NUMBER为1的行，则我们将为每个series_id获取一行，并且它将是max season_id中具有max episode_id的那一行。