TABLE A 下面是一个多对多表，我有它引用同一个表 TABLE X，我还有另一个 TABLE B 也引用了 TABLE X。我想创建一个映射这两个表的查询。
表A
measure_id | related_measure_id
1 | 2
1 | 4
1 | 5
2 | 3
2 | 4
2 | 6
3 | 5
表B
id | name | measure_id
A | Adam | 1
B | Bill | 2
C | Cate | 2
D | Dale | 3
E | Emma | 3
F | Fawn | 4
G | Gale | 5
H | Hale | 5
I | Iale | 5
J | Jake | 6
期望的输出:
id | name | id2 | name2
A | Adam | B | Bill
A | Adam | C | Cate
A | Adam | F | Fawn
A | Adam | G | Gale
A | Adam | H | Hale
A | Adam | I | Iale
B | Bill | D | Dale
B | Bill | E | Emma
B | Bill | F | Fawn
B | Bill | J | Jake
C | Cate | D | Dale
C | Cate | E | Emma
C | Cate | F | Fawn
C | Cate | J | Jake
D | Dale | H | Hale
D | Dale | I | Iale
E | Emma | H | Hale
E | Emma | I | Iale
尝试:
select b.id, b.name
from tableB b
join tableA a1 on b.measure_id=a1.measure_id
join tableA a2 on b.measure_id=a2.related_measure_id
最佳答案
在 db-fiddle 上测试过，应该可以。
SELECT B1.id AS id, B1.name AS name, B2.id AS id2, B2.name AS name2
FROM tableA AS A
JOIN tableB AS B1
ON A.measure_id = B1.measure_id
JOIN tableB AS B2
ON A.related_measure_id = B2.measure_id
关于MYSQL 多对多查询同一张表，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/54524670/