MySQL:搜索 child 记录

Question

假设有 2 个表:

TABLE: team
-----------
| team_id |
===========
| 1       |
-----------
| 2       |
-----------

TABLE: team_member
-------------------------------------------
| team_member_id | team_id | age | gender |
===========================================
| 1              | 1       | 20  | Male   |
-------------------------------------------
| 1              | 2       | 25  | Male   |
-------------------------------------------
| 1              | 2       | 23  | Female |
-------------------------------------------

如何搜索这样的内容:

1. 所有年龄在 18 至 25 岁之间的男性团队的列表。
2. 所有男性和女性团队的列表，其中任一性别的年龄在 18 至 25 岁之间。
3. 等等

我基本上正在寻找有关如何在team的所有子记录中应用某些过滤器(例如年龄)的一般策略。有建议吗？

Answer 1

团队，团队成员

如果您仅检查全男性或全女性团队，则不能只应用简单的 WHERE 子句...它需要与全套团队成员进行比较。尝试一下

select 
      tm.team_id,
      sum( if( tm.gender = 'Male' AND tm.age between 18 and 25, 1, 0 )) as MaleInRange,
      count(*) AllTeamMembers
  from
      team_member tm
  group by
      tm.Team_ID
  having
      MaleInRange = AllTeamMembers

同样，为了确保您同时拥有男性和女性......

select 
      tm.team_id,
      sum( if( tm.age between 18 and 25, 1, 0 )) as AgeInRange,
      sum( if( tm.gender = 'Male', 1, 0 )) as MaleCnt,
      sum( if( tm.gender = 'Female', 1, 0 )) as FemaleCnt,
      count(*) AllTeamMembers
  from
      team_member tm
  group by
      tm.Team_ID
  having
         AgeInRange = AllTeamMembers
     AND MaleCnt > 0
     AND FemaleCnt > 0