Sql Postgres-仅为一对多关系获取一行

我在博士后有两张桌子。它们之间存在一对多的关系

经理表

Id    Designation  
1     Manager

Id    Designation  Report_To (ManagerId) 
4     INFRA ENG    1
2     SOFT ENG     1
3     TEAM LEAD    1

团队成员表

Id    Designation  
1     Manager

Id    Designation  Report_To (ManagerId) 
4     INFRA ENG    1
2     SOFT ENG     1
3     TEAM LEAD    1

我必须以这样一种方式获取记录，即对于指定TeamMember为单独列的经理，我只能获得一行记录，如下所示：

结果：

ManagerId    INFRA  SOFT  TEAM
1            4      2     3

我尝试了左连接，但它给了我3行

---

他非常感谢您的帮助。

您可以执行条件聚合：

select report_to as manager_id, 
    max(id) filter(where designation = 'INFRA ENG') as infra,
    max(id) filter(where designation = 'SOFT ENG')  as soft,
    max(id) filter(where designation = 'TEAM LEAD') as team
from teammember 
group by report to

请注意，您无需携带

管理器

表即可获得显示的结果。但如果您出于其他原因需要它，您可以

加入

：

select m.*, 
    max(tm.id) filter(where tm.designation = 'INFRA ENG') as infra,
    max(tm.id) filter(where tm.designation = 'SOFT ENG')  as soft,
    max(tm.id) filter(where tm.designation = 'TEAM LEAD') as team
from manager m
inner join teammember tm on tm.report_to ) m.id
group by m.id