获取连接和分组查询中的总行数

Question

我的 rails 应用程序中有一个相当复杂的查询，我加入 table A 和 table B 这样我就可以彻底搜索两个 tables 然后，我在其 ID 上对 table A 进行分组，以删除由我在 table B 上的内部联接创建的重复项然后我需要剩余记录的计数，以便我可以对结果进行分页。

但是这样做会在我尝试获取计数时出现以下异常：

ActiveRecord::StatementInvalid (PG::AmbiguousColumn: ERROR:  column reference "game_id" is ambiguous
LINE 1: SELECT COUNT(*) AS count_all, game_id AS game_id, region AS ...
                                      ^
: SELECT COUNT(*) AS count_all, game_id AS game_id, region AS region FROM "game_data" INNER JOIN "player_participants" ON "player_participants"."game_id" = "game_data"."game_id" WHERE "player_participants"."region" =  AND "game_data"."region" = 'NA1' AND "game_data"."status" = 1 GROUP BY "game_data"."game_id", "game_data"."region"):

这是我的 rails 代码：

games = GameDatum.joins(:player_participants).where(
  player_participants: pp_data,
  game_data: g_data
).group(:game_id).order(created_at: :desc).page(page).per(records)

games_json = {}
games_json[:pages] = games.total_pages

games.total_pages 使用 .count，这是给我带来问题的原因。

感谢您的帮助！

Answer 1

ERROR:  column reference "game_id" is ambiguous

您的两个 table 中似乎都有 game_id 列。因此，请在查询中使用 table_name.column_name 约定。如果要使用 player_participants table:

中的 game_id，请使用 .group('player_participants.game_id') 而不是 group(:game_id)

  games = GameDatum
    .joins(:player_participants)
    .where(player_participants: pp_data, game_data: g_data)
    .group('player_participants.game_id')
    .order(created_at: :desc)
    .page(page)
    .per(records)

Answer 2

从纯粹的 SQL 答案来看，问题是 game_id 出现在两个表中，因此您需要在查询中具体说明要使用哪个表，例如：

SELECT COUNT(*) AS count_all, "player_participants".game_id AS game_id, region AS region FROM "game_data" INNER JOIN "player_participants" ON "player_participants"."game_id" = "game_data"."game_id" WHERE "player_participants"."region" =  AND "game_data"."region" = 'NA1' AND "game_data"."status" = 1 GROUP BY "game_data"."game_id", "game_data"."region"

因此我建议您尝试通过以下方式将 table.column_name 添加到您的组中：

.group('player_participants.game_id')

抱歉，我无法提供更多帮助。

获取连接和分组查询中的总行数

Get total rows in joined and grouped query

ruby-on-rails

kaminari