之前不太懂怎么多表联查，目前实现了3个表的查询方式记录一下
join on
找到两两表的关系的字段，需要将字段标注出来之后就是查询了
select c.plate_number from crm_car c
join crm_customer_car b
on b.car_id = c.id
join crm_customer a
on a.id = b.customer_id where a.id = 'JC-LXQQ-1112'
