sql连接三张表格

引自

https://blog.csdn.net/megamind_hl/article/details/79268552

在做开发的时候，有时候会遇到多张表的连接查询，写两张表的连接查询，都会觉得很简单，但是超过这个数量的时候，可能会觉得难，其实，只要你分清楚表和字段，多表查询也能简单解决：

//这是三张表的左连接查询；
select DISTINCT  t1.* 
FROM crm_wy_fee_record t1 
LEFT JOIN crm_wy_fee_record_detail t2 on t1.order_no = t2.order_no
LEFT JOIN crm_owner_residence t3 on t2.residence_code = t3.residence_code
WHERE t3.owner_id =#{owner_id}

 

//三张表的左连接和全连接混合；
SELECT DISTINCT t2.residence_code as room_code,t1.* 
FROM crm_wy_fee_record_detail t2 
INNER JOIN crm_wy_fee_record t1 on t1.order_no = t2.order_no
LEFT JOIN crm_owner_residence t3 on t2.residence_code = t3.residence_code 
WHERE t3.owner_id = #{owner_id}