mysql根据字段值关联查不同表：

实现：

 使用left join 结合case when 判断直接取值：

select mp.member_id ,mp.store_id,
case mp.store_type 
      when  1 then bs.store_name
      when  2 then sc.store_name
      when 3 then be.store_name end as 'store_name'
  from  mc_profiles mp  
left join bas_store bs on bs.id=mp.store_id
left join bas_sports_city sc on sc.id=mp.store_id
left join bas_extros be.id=mp.store_id