在 Having 子句中使用 2 聚合

Question

如果我有 table 包含来自多个联赛的所有球队的数据，我如何才能获得每个联赛的第一支球队？每个联赛中的第一支球队应该是得分最多的球队，或者如果得分相等则净胜球最好的球队 (GF-GA)

例如：

League	Team	GF	GA	Points
Champion Group A	Bayren	18	5	16
Champion Group A	Atlteico Madrid	7	8	9
Champion Group H	PSG	13	6	12
Champion Group H	RB Leipzig	11	12	12

我想得到这样的结果：

League	Team
Champion Group A	Bayren
Champion Group H	PSG

SELECT TEAM, LEAGUE
FROM LEAGUES_TABLE
GROUP BY LEAGUE
HAVING MAX(POINTS)  //or if point equal use MAX(GF-GA)

Answer 1

试试这个。我没有对此进行测试，但在我看来，这应该可行。

with team_points_ranked as (SELECT TEAM, LEAGUE, GA, GF
FROM LEAGUES_TABLE
GROUP BY LEAGUE
HAVING MAX(POINTS))

select TEAM, LEAGUE
from team_points_ranked
group by LEAGUE
having MAX(GF-GA)

Answer 2

您可以使用 ROW_NUMBER() window 函数：

SELECT league, team, gf, ga, points
FROM (
  SELECT *, ROW_NUMBER() OVER (PARTITION BY league ORDER BY points DESC, gf - ga DESC) rn
  FROM leagues_table
)
WHERE rn = 1

或 NOT EXISTS:

SELECT lt1.* FROM leagues_table lt1
WHERE NOT EXISTS (
  SELECT 1 FROM leagues_table lt2
  WHERE lt2.league = lt1.league 
    AND (lt2.points > lt1.points 
         OR (lt2.points = lt1.points AND lt2.gf - lt2.ga > lt1.gf - lt1.ga)
        ) 
)

或使用相关子查询：

SELECT lt1.* FROM leagues_table lt1
WHERE lt1.rowid = (
  SELECT lt2.rowid
  FROM leagues_table lt2
  WHERE lt2.league = lt1.league
  ORDER BY lt2.points DESC, lt2.gf - lt2.ga DESC
)

参见demo。
结果：

League	Team	GF	GA	Points
Champion Group A	Bayren	18	5	16
Champion Group H	PSG	13	6	12

在 Having 子句中使用 2 聚合

Using 2 Aggregation in Having Clause

sqlite

having-clause