如何将2个表与另一个3rd表中的公共列联接？

Question

我想将表 people 与表 video 联接在一起，但他们之间没有直接的公共列，但两个表的表与 village < / strong>，请帮助我加入表人和表视频。

人

id                 village_id
 1                 smg

视频

id               village_id
 1                 smg  

村庄

id               name
smg                hdd

我尝试了以下代码，但无法正常工作：

SELECT people.id, video.id
FROM people
JOIN village ON people.village_id = village.id
JOIN video ON video.village_id = village.id

Answer 1

如果您提供的表格结构正确，那么您在视频和人物之间确实存在链接。您有village_id ...

SELECT p.id , vid.id 
FROM people  as p 
INNER JOIN video as vid 
    ON vid.village_id = p.village_id 

如果您不希望有任何重复的值，则可以像这样SELECT DISTINCT

SELECT DISTINCT p.id , vid.id 
FROM people  as p 
INNER JOIN video as vid 
    ON vid.village_id = p.village_id 

您能否提供有关您到底想要什么的更多详细信息？

Answer 2

SELECT  * FROM

(SELECT people.village_id AS pv_id, village.id AS v_id FROM
people JOIN village ON people.village_id = village.id) AS T

JOIN video ON video.village_id = T.v_id;

我假设您要进行三次JOIN。我首先将人和村庄合并到一个表中，并将其命名为T，然后将T与视频表合并。