Question

我有以下表格：

1. club_members (id, type, name)
2. male_members (name, age, location)
3. female_members (name, age, location)
4. senior_members (name, age, location)

我需要根据从第一个表中检索的类型选择这3个表中的一个。与type=male一样，我会从male_members中选择，依此类推。

所以我想写一个类似于

的查询

select type, name , age , location from club_members , (2/3/4 table) where id=X ...

如何编写此类查询。

可能正在使用 if/else 或 case 语句

Answer 1

假设名称为表格之间的链接。

select 
       C.type as Type,
       COALESCE(m.name, f.name, s.name) AS MemberName, 
       COALESCE(m.age, f.age, s.age) AS MemberAge, 
       COALESCE(m.location, f.location, s.location) AS Location
from club_members C
left join male_members M on C.name=M.name and C.type='Male'
left join female_members F on C.name=F.name and C.type='Female'
left join senior_members S on C.name=S.name and C.type='Senior'
where C.id='Your value'

MySQL查询 - 根据前提条件（从不同的表中检索的值）连接不同的表

1 个答案: