MYSQL表关联删除

MYSQL表关联删除

#4张表关联删除

DELETE sp,sps,spt,sst 
FROM `sys_preset` sp 
LEFT JOIN sys_preset_type spt ON sp.type_id=spt.type_id 
LEFT JOIN sys_preset_scene sps ON sp.scene_id=sps.scene_id  
LEFT JOIN sys_stay_t sst ON sp.stay_id=sst.stay_id
WHERE preset_id=3

单表的级联查询  省市县村

案例

SELECT
    a2.area_id AS parent_id,
    a2.area_name AS parent_name,		
    a1.area_id AS child_id,
    a1.area_name AS child_name
FROM AREA AS a1
    LEFT JOIN AREA AS a2 
    ON a1.parent_id = a2.area_id
----------
SELECT 
    sa.area_name
FROM `sys_area` sa
    LEFT JOIN `sys_area` sa1
    ON sa.area_code=sa1. parent_code

关联查询3张表的中的另外2张表的所有数据 

#查询设备信息，站址信息数据

SELECT 
  sm.*,ssi.* 
FROM `sys_monitoring` sm 
INNER JOIN `sys_monitoring_status` sms 
ON sms.`monitoring_id` = sm.`monitoring_id` 
INNER JOIN `sys_site_information` ssi 
ON sms.`status` = ssi.`status` 
WHERE sms.`status` = 0