Question

我需要编写一个SQL查询，它连接三个表。

表格是：

Hotels：id |名字| nz |照片|价格|标准| idcountry
Countries：id |名称
home_promo：id | idhotel

我的查询是：

SELECT 
    h.id, h.name, h.nz, h.photo, h.price, h.standard,
    h.idcountry, k.name as k_name 
FROM hotels as h 
LEFT JOIN coutries AS k ON k.id=h.idcountry 
LEFT JOIN home_promo AS hm ON hm.idhotel=h.id 
WHERE h.publications=1

但它返回酒店表中的所有记录。有人可以帮忙吗？

Answer 1

如果您只想要那些位于home_promo中的酒店ID，那么

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Answer 2

这应该可以解决问题：

SELECT h.id,h.name,h.nz,h.photo,h.price,h.standard,h.idcountry,k.name as k_name 
FROM hotels as h 
JOIN home_promo AS hm ON hm.idhotel=h.id 
LEFT JOIN coutries AS k ON k.id=h.idcountry 
WHERE h.publications=1

虽然您可能想要从国家/地区中删除LEFT，因为离开它仍然会返回没有匹配国家/地区的酒店的结果。

Answer 3

如果home_promo和国家/地区的ID匹配，则此查询将起作用

SELECT h.id,h.name,h.nz,h.photo,h.price,h.standard,h.idcountry,k.name as k_name 
FROM hotels as h 
LEFT JOIN coutries AS k ON h.idcountry = k.id 
LEFT JOIN home_promo AS hm ON h.id = hm.idhotel
WHERE h.publications=1

LEFT JOIN不起作用

3 个答案: