select 用户id,count(1) as 订单数量 from 订单表 group by 用户id
select b.站名 as 起始站,c.站名 as 终点站 from 线路表 a left join 车站信息表 b on a.起始站=b.id left join 车站信息表 c on a.终点站=c.id
