MySQL CONCAT multiple unique rows - mysql

Question

So, here's basically the problem:
For starter, I am not asking anyone to do my homework, but to just give me a nudge in the right direction.
I have 2 tables containing names and contact data for practicing
Let's call these tables people and contact.
Create Table for people:
CREATE TABLE `people` (
`id` int(10) unsigned NOT NULL AUTO_INCREMENT,
`fname` tinytext,
`mname` tinytext,
`lname` tinytext,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1
Create Table for contact:
CREATE TABLE `contact` (
`id` int(10) unsigned NOT NULL AUTO_INCREMENT,
`person_id` int(10) unsigned NOT NULL DEFAULT '0',
`tel_home` tinytext,
`tel_work` tinytext,
`tel_mob` tinytext,
`email` text,
PRIMARY KEY (`id`,`person_id`),
KEY `fk_contact` (`person_id`),
CONSTRAINT `fk_contact` FOREIGN KEY (`person_id`) REFERENCES `people` (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1
When getting the contact information for each person, the query I use is as follows:
SELECT p.id, CONCAT_WS(' ',p.fname,p.mname,p.lname) name, c.tel_home, c.tel_work, c.tel_mob, c.email;
This solely creates a response like:
+----+----------+---------------------+----------+---------+---------------------+
| id | name | tel_home | tel_work | tel_mob | email |
+----+----------+---------------------+----------+---------+---------------------+
| 1 | Jane Doe | 1500 (xxx-xxx 1500) | NULL | NULL | janedoe#example.com |
| 2 | John Doe | 1502 (xxx-xxx 1502) | NULL | NULL | NULL |
| 2 | John Doe | NULL | NULL | NULL | johndoe#example.com |
+----+----------+---------------------+----------+---------+---------------------+
The problem with this view is that row 1 and 2 (counting from 0) could've been grouped to a single row.
Even though this "non-pretty" result is due to corrupt data, it is likely that this will occur in a multi-node database environment.
The targeted result would be something like
+----+----------+---------------------+----------+---------+---------------------+
| id | name | tel_home | tel_work | tel_mob | email |
+----+----------+---------------------+----------+---------+---------------------+
| 1 | Jane Doe | 1500 (xxx-xxx 1500) | NULL | NULL | janedoe#example.com |
| 2 | John Doe | 1502 (xxx-xxx 1502) | NULL | NULL | johndoe#example.com |
+----+----------+---------------------+----------+---------+---------------------+
Where the rows with the same id and name are grouped when still showing the effective data.
Side notes:
innodb_version: 5.5.32
version: 5.5.32-0ubuntu-.12.04.1-log
version_compile_os: debian_linux-gnu

Answer 1

You could use GROUP_CONCAT(), which "returns a string result with the concatenated non-NULL values from a group":
SELECT p.id,
GROUP_CONCAT(CONCAT_WS(' ',p.fname,p.mname,p.lname)) name,
GROUP_CONCAT(c.tel_home) tel_home,
GROUP_CONCAT(c.tel_work) tel_work,
GROUP_CONCAT(c.tel_mob ) tel_mob,
GROUP_CONCAT(c.email ) email
FROM my_table
GROUP BY p.id