SQL选择具有多个值的内部联接答案

【问题标题】：SQL Select inner join with multiple valueSQL选择具有多个值的内部联接
【发布时间】：2023-02-16 00:07:57
【问题描述】：

是否可以在一个 select 语句中获取所有值？

从下面的 SQL 语句中注意，province_name 和 city_name 引用同一列并使用 ID ...

这是sql语句：

SELECT CLIENT.name,
       CLIENT.province_id, CANADA.name as province_name,
       CLIENT.city_id,     CANADA.name as city_name
FROM ((CLIENT
INNER JOIN CANADA as ON CLIENT.province_id = CANADA.id)
INNER JOIN CANADA as ON CLIENT.city_id = CANADA.id)
WHERE CLIENT

为了更好地理解我的意思，这是 CANADA 表的结构

CANADA_id	name	id	parent_id
1	Canada	1000	0
2 (Province)	Alberta	1100	1000
3 (Province)	British Columbia	1200	1000
4 (city)	Banff	1101	1100
5 (city)	Calgary	1102	1100
6 (city)	Victory	1201	1200
7 (city)	Vancouver	1202	1200

我想返回如下表...

name	province_id	province_name	city_id	city_name
John	1100	Alberta	1102	Calgery

非常感谢你的帮助。

【问题讨论】：

标签： sql select inner-join

【解决方案1】：

SELECT CLIENT.name,
       CLIENT.province_id, CANADA_province.name as province_name,
       CLIENT.city_id,     CANADA_city.name as city_name
FROM CLIENT
INNER JOIN CANADA as CANADA_province
    ON CLIENT.province_id = CANADA_province.id
INNER JOIN CANADA as CANADA_city
    ON CLIENT.city_id = CANADA_city.id
WHERE CLIENT.name IS NOT NULL
AND CLIENT.province_id IS NOT NULL
AND CLIENT.city_id IS NOT NULL;

【讨论】：