mysql - 按两列分组

Question

数据库表包含目标操作。

 type      goal      assist
 goal      Johnny    James
 goal      Johnny    James
 goal      James     Bob

使用GROUP BY goal, Assist时显示

 player    goals     assists
 Johnny    2         0
 Johnny    0         0
 James     1         0
 James     0         2
 Bob       0         0
 Bob       0         1

但我需要它在一行中显示球员的进球和助攻。干杯。

Answer 1

您可以这样做(尽管这可能不是最快的查询，具体取决于数据库和索引的大小!):

SELECT players.player,
      -- Use correlated subselects to count goals / assists
      (SELECT COUNT(*) FROM actions WHERE goal = players.player) goals
      (SELECT COUNT(*) FROM actions WHERE assist = players.player) assists

-- Get all distinct players (UNION = DISTINCT, here). Of course, if you
-- have an actual players table, use that one instead!
FROM (
  SELECT goal player FROM actions UNION
  SELECT assist      FROM actions
) players

根据您的问题，我不确定 type = goal 是否与您的查询相关...