MySQL 按连接分组

Question

我有两个 SQL 表。 客户和标签加入customer.id=tag.attach_id

customer
+------+-------------+--------------+
|  id  |   name      |   email      |
|  9   |   Alan      |  alan@me.com |
+------+-------------+--------------+

tag
+------+-------------+--------------+
| id   | attach_id   | content      |
| 1    |   9         | alan-tag     |
| 2    |   9         | second-tag   |
+------+-------------+--------------+

我想输出这个：

+-------+-----------------+-----------------------+
| name  |     email       | content               |
+-------+-----------------+-----------------------+
| alan  | alan@me.com     | alan-tag, second-tag  |
+-------+-----------------+-----------------------+

这是我对 SQL 的最佳尝试：

SELECT customer.name, customer.email, tag.content
FROM customer
INNER JOIN tag
ON customer.id=tag.attach_id
GROUP BY customer.id,tag.content;

如果不先用另一种语言（如 PHP）处理数据，这是否可能？

Answer 1

是的，您需要按照评论区其他人的建议使用 GROUP_CONCAT，更具体地说（确切地说）您的查询是

SELECT `name`, email, GROUP_CONCAT(tag.content SEPARATOR ', ') as content
FROM
customer
INNER JOIN tag ON customer.id = tag.attach_id
GROUP BY customer.id

此查询将为您提供您在帖子中发布的确切结果

Answer 2

如果你使用的是sql，你可以使用listagg

select c.name,email,listagg(content,',') within group (order by c.name) "content"
from customer c, tag t
where c.id = t.attach_id
group by c.name,email

Answer 3

使用这个：

SELECT customer.name, customer.email, GROUP_CONCAT(tag.content SEPARATOR ', ') as content
FROM customer
INNER JOIN tag
ON customer.id=tag.attach_id
GROUP BY customer.id;