mysql - 向重复记录添加附加数据

Question

我有这个代码可以检查有多少重复代码:

mysql> SELECT code, count(code) as dup from tg_user group by code having dup>1 order by dup;

返回:

+------------+-----+
| CCC002     |   5 |
| BAR003     |   6 |
| FIR001     |   6 |
| NJS001     |   6 |
| DEL004     |   6 |
| BRA009     |   7 |
| TSH011     |  11 |
| SHO005     |  19 |
+------------+-----+
432 rows in set (0.08 sec)

表结构为:

mysql> describe tg_user;
+---------------+--------------+------+-----+---------+----------------+
| Field         | Type         | Null | Key | Default | Extra          |
+---------------+--------------+------+-----+---------+----------------+
| user_id       | int(11)      | NO   | PRI | NULL    | auto_increment |
| user_name     | varchar(30)  | YES  | UNI | NULL    |                |
| email_address | varchar(255) | YES  | UNI | NULL    |                |
| code          | varchar(25)  | YES  |     | NULL    |                |
+---------------+--------------+------+-----+---------+----------------+
32 rows in set (0.00 sec)

为每个重复记录添加电子邮件地址的正确方法是什么，以便它作为列表出现，如下所示:

| SHO005     |  19 | name@domai.tld, name@domai.tld...       |
+------------+-----+-----------------------------------------+
432 rows in set (0.08 sec)

非常感谢任何建议

Answer 1

GROUP_CONCAT 用逗号连接值。 添加 DISTINCT 以过滤掉重复项

SELECT code, count(code) as dup, GROUP_CONCAT(DISTINCT email_address)
from tg_user group by code having dup>1 order by dup;