mysql，关联表查询

Question

第一张表的cityId1、cityId2、cityId3和第二张表的id关联，怎样把第一张表查出，并且把相应的cityId1、cityId2、cityId3换成对应的地区的名字？

Answer 1

select
t1.id, a.name as city1,
b.name as city2,
c.name as city3,
t1.name
from table1 as t1
left join table2 as a on t1.city1=a.id
left join table2 as b on t1.city2=b.id
left join table2 as c on t1.city3=c.id

Answer 2

你这个是一个层级维度表，有个问题就是你如果维度表是无限级的话，只有在生成的时候操作了。