MySQL加入分组没有完美加入

Question

我有三个表并想加入它们，但是当使用联系人表中的父 ID 分组时，加入会多次返回单行。

contact表-

id	Name
1	Murad
2	Tajharul

phone表-

id	contact_id	phone
1	1	017
2	2	014
3	2	015

email表-

id	contact_id	email
1	1	mur@test.com
2	1	has@test.com
3	1	tan@test.com
4	2	taj@test.com
5	2	har@test.com

期望的输出-

id	Name	Phone	Email
1	Murad	017	mur@test.com,has@test.com,tan@test.com
2	Tajharul	014,015	taj@test.com,har@test.com

这是我迄今为止尝试过的-

SELECT contact.name , GROUP_CONCAT(phone.phone) phone, GROUP_CONCAT(email.email) email
FROM 
    contact 
    JOIN phone ON contact.id = phone.contact_id
    JOIN email ON contact.id = email.contact_id
GROUP BY contact.id

MySQL Fiddle 链接：http://sqlfiddle.com/#!9/ded29f/1

Answer 1

在 group_concat 中使用 DISTINCT

SELECT contact.name , GROUP_CONCAT(DISTINCT phone.phone) phone, GROUP_CONCAT(DISTINCT email.email) email
FROM 
    contact 
    JOIN phone ON contact.id = phone.contact_id
    JOIN email ON contact.id = email.contact_id
GROUP BY contact.id

Answer 2

您可以通过在 Group concat 中使用子查询和 Distinct 来实现：

SELECT T1.id, T1.name, T1.phone, GROUP_CONCAT(DISTINCT email.email) email
FROM 
    (SELECT contact.id, contact.name , GROUP_CONCAT(DISTINCT phone.phone) phone
    FROM 
        contact 
        JOIN phone ON contact.id = phone.contact_id
  GROUP BY contact.id) T1
JOIN email ON T1.id = email.contact_id
GROUP BY T1.id