Mengalami masalah dalam menggabungkan HAVING dengan WHERE pada QUERY yang sangat sederhana

Saya tidak memiliki latar belakang PostgreSQL tetapi mari kita lihat apakah ini berfungsi:

Saya akan memulai ini dengan menyederhanakannya, dengan menulis kueri yang terlebih dahulu mengembalikan skor total menurut pemain:

SELECT player_id, SUM(score) score
FROM (
  SELECT first_player as player_id, first_score as score
  FROM matches
  UNION ALL
  SELECT second_player, second_score
  FROM matches
)
GROUP BY player_id

Sekarang, gabungkan kumpulan data itu ke pemain untuk menemukan grup:

SELECT w.player_id, p.group_id, w.score
FROM
(
  SELECT player_id, SUM(score) score
  FROM (
    SELECT first_player as player_id, first_score as score
    FROM matches
    UNION ALL
    SELECT second_player, second_score
    FROM matches
  )
  GROUP BY player_id
) as w
inner join players p
on p.player_id = w.player_id

Sekarang kami memiliki semua pemain, skor total dan grup mereka. Kami ingin mengidentifikasi pemenang berdasarkan kelompok? Kita dapat menggunakan peringkat berfungsi untuk melakukan ini:

SELECT 
w.player_id, 
p.group_id, 
w.score, 
RANK() OVER (PARTITION BY p.group_id ORDER BY score DESC) as group_placement
FROM
(
  SELECT player_id, SUM(score) score
  FROM (
    SELECT first_player as player_id, first_score as score
    FROM matches
    UNION ALL
    SELECT second_player, second_score
    FROM matches
  )
  GROUP BY player_id
) as w
inner join players p
on p.player_id = w.player_id

Sekarang kita tinggal memilih yang teratas di setiap grup (peringkat =1) menggunakan WHERE

  SELECT 
  player_id, 
  group_id
  FROM
  (
      SELECT 
      w.player_id, 
      p.group_id, 
      w.score, 
      RANK() OVER (PARTITION BY p.group_id ORDER BY score DESC) as group_placement
      FROM
      (
        SELECT player_id, SUM(score) score
        FROM (
          SELECT first_player as player_id, first_score as score
          FROM matches
          UNION ALL
          SELECT second_player, second_score
          FROM matches
        )
        GROUP BY player_id
      ) as w
      inner join players p
      on p.player_id = w.player_id
    ) as gp
    WHERE group_placement = 1

Terlihat rumit? ya, tetapi Anda dapat melihat hasil akhir disediakan sedikit demi sedikit. Setiap langkah ini adalah 'subtabel' dan Anda dapat menjalankan dan mengamati data di setiap titik.