Question

我有这些表格：

主机：

+----+------+---------+-------------+------------+--------+-----------------------+-----------------------+-------+
| id | name |   url   | environment | instanceId | region |      created_at       |      updated_at       | value |
+----+------+---------+-------------+------------+--------+-----------------------+-----------------------+-------+
|  4 | test | testing | qa          |  foo       |  bar   | "2017-09-23 14:57:18" | "2017-09-23 14:57:18" |  1222 |
+----+------+---------+-------------+------------+--------+-----------------------+-----------------------+-------+

ddframes：

+----+-------+-------+
| id | value | owner |
+----+-------+-------+
|  1 |  1222 |     4 |
|  2 |   333 |     4 |
|  3 |   444 |     4 |
+----+-------+-------+

ddframe上的

owner是id上hosts的外键

我想要的输出是：

+----+------+---------+-------------+------------+--------+-----------------------+-----------------------+--------------+
| id | name |   url   | environment | instanceId | region |      created_at       |      updated_at       |   ddframes   |
+----+------+---------+-------------+------------+--------+-----------------------+-----------------------+--------------+
|  4 | test | testing | qa          | hiri       | sdf    | "2017-09-23 14:57:18" | "2017-09-23 14:57:18" | 1222,333,444 |
+----+------+---------+-------------+------------+--------+-----------------------+-----------------------+--------------+

将ddframe连接在一起。

我拥有的是：

SELECT h.*, d.value as ddframes
FROM hosts h
INNER JOIN ddframes d
ON h.id = d.owner
GROUP BY h.id;

但它产生类似于我想要的输出的东西，只是没有其他ddframes。只有第一个。

这可以实现吗？也许我的桌子＆＃39;设计错了吗？

Answer 1

您需要group_concat()功能：

SELECT h.*, GROUP_CONCAT(d.value) as ddframes
FROM hosts h INNER JOIN
     ddframes d
     ON h.id = d.owner
GROUP BY h.id;

我应该注意。通常，在SELECT *查询中使用GROUP BY是个坏主意。假设hosts.id是唯一的（主键是），那么这是可以接受的。事实上，ANSI标准支持GROUP BY中唯一键的此构造。

加入表时，Concat一对多

1 个答案: