Where not Exists en Laravel - mysql

Question

Could anybody tell me what error I might have in my laravel query, basically what I want is to list the records of a table whose id is not related in another table. I did it in Mysql with this query: SELECT * FROM item WHERE NOT EXISTS (SELECT null FROM qualifications WHERE grades.item_id = item.id AND qualifications.user_id = 2);
but now I need to do this same query in laravel, I tried it this way:
codigo
and what I get is this syntax error that I do not know how to solve anymore:
error
I am very grateful to anyone who can tell me what I am doing wrong, or in what form I make that query in Laravel.

Answer 1

You can also rewrite your query as left join like
SELECT i.*
FROM item i
LEFT JOIN qualifications q ON q.item_id = i.id AND q.user_id = 2
WHERE q.item_id IS NULL
In query builder you can write it as
DB::table('item as i')
->select('i.*')
->leftJoin('qualifications as q', function ($join) use($user_id) {
$join->on('q.item_id', '=', 'i.id')
->on('q.user_id', '=', $user_id);
})
->whereNull('q.item_id')
->get();
Another approach which i suggest you to go with, is setup your relations and models and do it with eloquent way
class Item extends Model
{
public function qualifications()
{
return $this->hasMany(\App\Models\Qualification::class, 'item_id');
}
}
class Qualification extends Model
{
public function qualifications()
{
return $this->belongsTo(Item::class, 'item_id');
}
}
And then you can use Querying Relationship Absence
Item::whereDoesntHave('qualifications', function ($query) use($user_id) {
$query->where('user_id', '=', $user_id);
})->get();