Mysql SELECT display only 1 result instead of multiple from 3 tables - mysql

Question

I try to make one SQL request where I get all data from multiple tables. Problem start when one user have for example more "enforcement". But first lets look on code:
SELECT c.id, c.firstname, c.surname, c.email, c.process, c.search_work, c.note,
MAX(CASE WHEN cl.languageID = 1 THEN cl.skill ELSE '-' END)AS 'en',
MAX(CASE WHEN cl.languageID = 2 THEN cl.skill ELSE '-' END)AS 'ge',
ce.enforcement
FROM candidates AS c
LEFT JOIN candidates_language AS cl ON c.id = cl.candidates_id
LEFT JOIN candidates_enforcement as ce on c.id = ce.candidates_id
GROUP BY c.id, c.firstname, c.surname, c.email
As you can see from here I search above multiple tables with using foreign key on candidates ID.
For this purpouse here is how 2 tables looks like:
candidates
------------------------------------------------------------------------
| id | firstname | surname | email |
------------------------------------------------------------------------
| 22 | John | Doe | john#doe.com |
------------------------------------------------------------------------
| 23 | Peter | Miller | doe#john.com |
------------------------------------------------------------------------
candidates_enforcement
--------------------------------------------------
| id | candidates_id | enforcement |
--------------------------------------------------
| 1 | 22 | Advocate |
--------------------------------------------------
| 2 | 22 | Programmer |
--------------------------------------------------
| 3 | 23 | IT Admin |
--------------------------------------------------
candidates_id = foreign key from candidates. With my SQL request above result should looks like:
---------------------------------------------------------------------------------
| id | firstname | surname | email | enforcement
---------------------------------------------------------------------------------
| 22 | John | Doe | john#doe.com | Advocate, Programmer |
---------------------------------------------------------------------------------
| 23 | Peter | Miller | doe#john.com | IT Admin
---------------------------------------------------------------------------------
Unfortunately it display me ALWAYS only 1 result from "enforcement". So for cancidate with id 22 it is Advocate not Advocate, Programmer
Is there a chance someone can help me to find a way how to fix this?
Thanks
p.s. Working demo on FIDDLE
http://sqlfiddle.com/#!9/25b1b/1

Answer 1

You could use GROUP_CONCAT like this:
SELECT
candidates.id,
candidates.firstname,
candidates.surname,
candidates.email,
group_concat(DISTINCT candidates_enforcement.enforcement)
FROM
candidates
LEFT JOIN candidates_enforcement
ON candidates.id = candidates_enforcement.candidates_id
GROUP BY
candidates.id,
candidates.firstname,
candidates.surname,
candidates.email
Reference:
GROUP_CONCAT(expr)

Answer 2

You can use Group_Concat with the Distinct option
SELECT c.id,c.firstname,c.surname,c.email,group_concat(distinct ce.enforcement)
FROM candidates c
LEFT JOIN candidates_enforcement ce
ON c.id=ce.candidates_id
GROUP BY c.id,c.firstname,c.surname,c.email
The distinct option will help you remove off the redundant values.

Answer 3

As I understood you want both enforcement to show up when a person has two enforcement. The problem here is you are LEFT joining the candidates_enforcement table to candidate table.
LEFT join does is get the tuples from candidate table and joins the corresponding tuples from candidates_enforcement. There is only one tuple for candidate in candidate table. So it only shows up one time whether candidates_enforcement has many tuples for that particular candidate or not.
To correct this do a RIGHT JOIN. Or you can do the same LEFT JOIN, with tables swapped.
SELECT c.id, c.firstname, c.surname, c.email,ce.enforcement
FROM candidates AS c
RIGHT JOIN candidates_enforcement as ce on c.id = ce.candidates_id