mysql - mysql关联表到多个表

我有这样的表：

      map           table1           table2           table3
| aID | bID |   | bid | val |     | bid | val |    | bid | val |
-------------   -------------     -------------    -------------
|  1  |  1  |   |  1  |  20 |     |  3  |  10 |    |  4  |  15 |
-------------   -------------     -------------    -------------
|  1  |  2  |   |  1  |  22 |     |  3  |  23 |    |  4  |  25 |
-------------   -------------     -------------    -------------
|  1  |  3  |   |  2  |  15 |     |  3  |  14 |    |  4  |  11 |
-------------   -------------     -------------    -------------
|  2  |  3  |   |  2  |  23 |     |  5  |  32 |    |  2  |  3  |
-------------
|  2  |  4  |
-------------

像这样尝试：

SELECT val, bid
   FROM map m
   RIGHT JOIN table1 t
     ON  m.bID =t.bid
   RIGHT JOIN table2 tt
     ON  m.bID =tt.bid
   RIGHT JOIN table3 ttt
     ON  m.bID =ttt.bid
   WHERE aID = 1

bID可以只是在tableX之一中

有没有一种简单的方法来检索aID 1的所有值？

最佳答案

试试这个查询

SELECT val, bid
FROM map m
LEFT JOIN table1 t
    ON  m.bID =t.bid
LEFT JOIN table2 tt
    ON  m.bID =tt.bid
LEFT JOIN table3 ttt
    ON  m.bID =ttt.bid
WHERE aID = 1

好的，根据您的评论，我编辑了我的帖子，尝试一下

SELECT val, bid
FROM map m
LEFT JOIN table1 t
    ON  m.bID =t.bid
WHERE aID = 1
UNION
SELECT val, bid
FROM map m
LEFT JOIN table2 tt
    ON  m.bID =tt.bid
WHERE aID = 1
UNION
SELECT val, bid
FROM map m
LEFT JOIN table3 ttt
    ON  m.bID =ttt.bid
WHERE aID = 1

关于mysql - mysql关联表到多个表，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/21723074/