mysql - 从与其所有者匹配的数据透视表中检索记录

Question

使用最新的 mariaDB 版本，我有以下表结构(例如修剪)

Table A
+--------+------+
| id     |name  |
+--------+------+
| 1      | Bob  |
| 2      | Jane |
+--------+------+

Table B
+--------+------+
| id     |city  |
+--------+------+
|      1 | abc  |
|      2 | def  |
|      3 | ghi  |
|      4 | jkl  |
+--------+------+

Pivot Table
+-----------+-----------+
| tableA_id | tableB_id |
+-----------+-----------+
|      1    |   1       |
|      1    |   3       |
|      2    |   3       |
|      2    |   4       |
+-----------+-----------+

有没有办法让它从这个输出中消失，还是需要用 php 来完成？

+--------+------+-------+
| id     |name  | city1 |
+--------+------+-------+
| 1      | Bob  |  abc  |
| 1      | Bob  |  ghi  |
| 2      | Jane |  ghi  |
| 2      | Jane |  jkl  |
+--------+------+-------+

为此:

+--------+------+----------+
| id     |name  | cities   |
+--------+------+----------+
| 1      | Bob  |  abc ghi |
| 2      | Jane |  ghi jkl |
+--------+------+----------+

当前使用下面的查询

SELECT c.id, c.city1, p.id pid, p.first_name FROM city c
INNER JOIN pivot_tablet piv ON c.id = piv.city_id
INNER JOIN person p ON p.id = piv.person_id

Answer 1

使用 group_concat()

SELECT p.id,p.first_name,group_concat(c.city1 SEPARATOR ' ') as cities, 
FROM pivot_tablet piv inner join city ON c.id = piv.city_id
INNER JOIN person p ON p.id = piv.person_id
group by p.id, p.first_name