场景【1】多表联查时,主表与关联表同时与同一张(第三张表)有关联,类似三角恋关系- -
涉及表:
- HOUSE:记录了房屋信息
- ROOMS:记录了房间信息
- HOUSE_STATUS:记录了状态信息的中文字段
房屋信息HOUSE表中有一个关于记录房屋状态的字段,status_id,与HOUSE_STATUS的主键表关联,而房间信息ROOMS表中,也有一个关于记录房屋状态的字段,也是status_id,当HOUSE与ROOMS建立关联查询时,两张表又分别需要与HOUSE_STATUS这张表建立关联查询。则出现了标题说的三角恋关系,查询方式只需要利用别名查询即可:
SELECT
HOUSE.ID,
HOUSE.NAME,
HOUSE.FLOOR,
HOUSE.EXPECT_PRICE,
HOUSE.AREA_NUMBER,
HOUSE.HAVE_KITCKEN,
HOUSE.HAVE_BALCONY,
PROVINCE.provinceName,
CITY.cityName,
AREA.areaName,
COMMUNITY.ID community_ID,
COMMUNITY.NAME community_Name,
HOUSE_LAYOUT.NAME layout_Name,
DECORATION_TYPE.NAME decorationType_Name,
HOUSE_STATUS.STATUS_NAME houseStatus_Name,
PAYMENT.PAYMENT_NAME payment_Name,
RENT_MODE.ID rentMode_ID,
RENT_MODE.NAME rentMode_Name,
ROOMS.ID,
ROOMS.ROOM_NO,
ROOMS.HOUSE_STATUS_ID,
ROOMS.AREA_NUMBER,
ROOMS.EXPECT_PRICE,
ROOMS.HAVE_WASHROOM,
ROOMS.HAVE_KITCKEN,
ROOMS.HOUSE_STATUS_ID,
ROOMS.HAVE_DESK,
ROOMS.HAVE_AIRCONDITIONING,
ROOMS.HAVE_WARDROBE,
ROOMS.HAVE_WATERHEATER,
ROOMS.HAVE_WLAN,
rooms_Status.ID rooms_StatusID,
rooms_Status.STATUS_NAME rooms_StatusName
FROM HOUSE
JOIN PROVINCE ON HOUSE.PROVINCE_ID = PROVINCE.provinceID
JOIN CITY ON HOUSE.CITY_ID = CITY.cityID
JOIN AREA ON HOUSE.AREA_ID = AREA.areaID
JOIN COMMUNITY ON HOUSE.COMMUNITY_ID = COMMUNITY.ID
JOIN HOUSE_LAYOUT ON HOUSE.LAYOUT_ID = HOUSE_LAYOUT.ID
JOIN DECORATION_TYPE ON HOUSE.DECORATION_TYPE_ID = DECORATION_TYPE.ID
JOIN HOUSE_STATUS ON HOUSE.HOUSE_STATUS_ID = HOUSE_STATUS.ID
JOIN PAYMENT ON HOUSE.EXPECT_PAYMENT_ID = PAYMENT.ID
JOIN HOUSE_RENT_MODE ON HOUSE.ID = HOUSE_RENT_MODE.HOUSE_ID
JOIN RENT_MODE ON HOUSE_RENT_MODE.RENT_MODE_ID = RENT_MODE.ID
JOIN ROOMS ON HOUSE.ID = ROOMS.HOUSE_ID
JOIN HOUSE_STATUS rooms_Status ON ROOMS.HOUSE_STATUS_ID = rooms_Status.ID
WHERE HOUSE.ID = 1