Question

我有一个查询可以完成一些事情。首先，它应该让所有团队的divisionid为1.然后它应该获得在结果列中注册的胜利数量。

它实现了这一点，但是如果团队在结果表中没有注册数据，则不会显示TeamName 0（wins）。关于为什么会发生这种情况的任何想法？

表1：活跃团队

 aid teamid divisionid
  1    1        1
  2    2        1
  3    3        1
  4    4        2

表2：团队

  teamid teamname 
    1     Argos
    2     Leafs 
    3     Blue Jays
    4     Ducks

表3：结果摆脱teamid的结果 1 1'w' 2 2'l'

最终结果目标

 divid teamname  wins
   1     Argos    1
   1     Leafs    0
   1     Bluejays 0

当前查询

SELECT activeteams.divisionid, teams.teamname, res.wins
FROM activeteams
JOIN teams ON activeteams.teamid = teams.teamid
  OUTER JOIN (
    SELECT 
      COALESCE(SUM(CASE WHEN result =  'w' THEN 1 ELSE 0 END ), 0) AS wins, 
      results.teamid AS teamid
  FROM results
  GROUP BY results.teamid
  )res ON teams.teamid = res.teamid
WHERE activeteams.divisionid = 1

Answer 1

你可以试试这个：

SELECT activeteams.divisionid, teams.teamname, res.wins
FROM activeteams
INNER JOIN teams ON activeteams.teamid = teams.teamid
LEFT JOIN (
    SELECT 
        COALESCE(SUM(CASE WHEN result =  'w' THEN 1 ELSE 0 END ), 0) AS wins, 
        teamid
    FROM results
    GROUP BY teamid
  ) res ON teams.teamid = res.teamid
WHERE activeteams.divisionid = 1

外连接 - 不工作，不显示空行

1 个答案: