MySQL Many to Many select - php

Question

I'm trying to create a MySQL Many to Many select query. I have three tables:
Profiles
Skills
Profile_skills (Profile ID and Skills ID)
I want to be able to search for a skill (PHP for example) and all profiles with that skill show up in a list, but including all their other skills. Like most freelance sites, so I can also see that they know MySQL etc.
I haven't found or figured out the correct way to get all info about a profile including all their skills. This is my best result so far:
SELECT * FROM profiles INNER JOIN profile_skills ON
profile_skills.profil_id = profiles.profil_id INNER JOIN skills ON
skills.skill_id = profile_skills.skill_id WHERE skill = 'PHP'
But this only gives me the profile with that one skill and not the rest.
Result:
http://imgur.com/E9PEiaU
Expected:
To have the id, Skill "PHP", and the rest of skills, for example "C#" if user id 1 possesses that skill.
http://imgur.com/5bCG4qo
So like this when I search for a profile with a skill, it also shows the rest of that profiles acquired skills.

Answer 1

You can re-join the profile_skills and skills table to get the result you want.
SELECT p.*, s2.*
FROM skills s1
INNER JOIN profile_skills ps1 ON s.skill_id = ps1.skill_id
INNER JOIN profiles p ON ps1.profil_id = p.profil_id
INNER JOIN profile_skills ps2 ON p.profil_id = ps2.profil_id
INNER JOIN skills s2 ON ps2.skill_id = s2.skill_id
WHERE s1.skill = 'PHP'
This will get you a result like this:
| p.id | p.name | s.id | s.skill |
---------------------------------------------
| 1 | rasmus | 1 | PHP |
| 1 | rasmus | 2 | Linux |
| 2 | thomas | 1 | PHP |
| 2 | thomas | 3 | Eating Sandwiches |
There are various different ways to get each profile in one row with a list of skills. One way is with GROUP_CONCAT in MySQL.
SELECT p.profil_id, p.profile_name, GROUP_CONCAT(s2.skill) AS skills
FROM skills s1
INNER JOIN profile_skills ps1 ON s.skill_id = ps1.skill_id
INNER JOIN profiles p ON ps1.profil_id = p.profil_id
INNER JOIN profile_skills ps2 ON p.profil_id = ps2.profil_id
INNER JOIN skills s2 ON ps2.skill_id = s2.skill_id
WHERE s1.skill = 'PHP'
GROUP BY p.profil_id
I added the profile_name column for example, since I don't know what your columns actually are, and you can add other ones, or even still use p.*. Technically, the other columns in profile aren't defined with GROUP BY p.profil_id, and you generally shouldn't select columns that aren't either included in the grouping or some aggregate function, but MySQL will take care of that for you in this case, since they'll all have the same values for each row with the same p.profil_id.
Another way is to just use the first query and do the grouping in PHP:
$previous_id = null;
while ($row = some_fetch_method()) {
if ($row['profil_id'] != $previous_id) {
echo "<h3>$row[profile_name]</h3>";
}
echo "<div>$row[skill]</div>";
}
obviously the HTML won't be quite what you need, but it should be enough to show the general idea.

Answer 2

You probably want a sub query to identify the accounts, and then load details about them with the super query (and GROUP_CONCAT the skills if you want). Something like:
SELECT profiles.*, GROUP_CONCAT(skills.skill SEPARATOR ', ') AS the_skillz
FROM profiles INNER JOIN profile_skills (...) INNER JOIN skills (...)
WHERE profiles.profile_id IN (
SELECT DISTINCT profile_id
FROM profile_skills INNER JOIN skills (...)
WHERE skills.skill = 'PHP'
)
GROUP BY profiles.profile_id;