Laravel Eloquent - Return unique values only and ignore all that appear more than once - sql

Question

I have 2 database tables.
|---------------------|------------------|
| Users | Matches |
|---------------------|------------------|
| user_id | match_id |
|---------------------|------------------|
| user_1 |
|------------------|
| user_2 |
|------------------|
with user_1 and user_2 being user_ids.
I am now trying to retrieve all matches with unique values only. As soon as a user ID is used twice, I don't want to retrieve ANY matches containing the id.
Example:
MATCHES (match_id, user_1, user_2):
1, 1, 2
2, 1, 3
3, 4, 5
4, 6, 7
5, 7, 8
The query should return 3, 4, 5 ONLY, because it's the only match containing only unique user_ids.
How should I go about this? I've been trying an approach using ->distinct() but that doesn't work since it only removes duplicates but I want to kick other entries containing the values as well.

Answer 1

Simple and crude, not a query based solution, but will get you what you want.
public function strictlyUniqueMatches()
{
$matches = Matches::distinct()->get();
$present = [];
foreach ($matches as $idx => $match) {
if (!isset($present[$match->user_1])) {
$present[$match->user_1] = 0;
}
if (!isset($present[$match->user_2])) {
$present[$match->user_2] = 0;
}
$present[$match->user_1]++;
$present[$match->user_2]++;
}
return $matches->filter(function ($match) use ($present) {
if ($present[$match->user_1] > 1) {
return false;
}
if ($present[$match->user_2] > 1) {
return false;
}
return true;
});
}