[英]group by and max on two columns
我有一個包含這些列的表:
id | series_id | season_id | episode_id | title | type ...
我想獲得具有唯一series_id
行,其中season_id
和episode_id
為最大值。
一種解決方案是這樣做:
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;
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
)
嘗試這個..
SELECT * FROM TABLE
HAVING MAX(season_id) AND MAX(episode_id)
GROUP BY series_id
:)
我認為這可能是過大了,但這是我發現對我有用的唯一方法。
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;
(對不起,樣本數據過多)
關鍵是,如果僅取最大的series_id和season_id,則對於這兩個系列,我們都不會獲得有效的對。 在這兩種情況下,第1季中的情節多於第2季。ROW_NUMBER()子句將每行返回一個唯一的編號,但是由於“ PARTITION BY”,它將針對每個series_id重新啟動(請參見注釋行)。 如果我們僅返回ROW_NUMBER為1的行,則每個series_id將獲得一行,並且它將是最大season_id中具有最大Episode_id的行。
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