Laravel the right way for Many to Many table structure - php

Question

I'm having a many to many relation. Lets say that I have Many users that can be in Many groups and the other way around.
I wan't to make a table that contains the following columns
group_user
id / name / user_id / group_id
Since I have only 3 groups Junior, Middle and Senior I don't want to make another separated table for them. My idea here is to make the following approach:
Creating 3 records in the same table group_user with the following data
id / name / user_id / group_id
1 / Junior / null / null
2 / Middle / null / null
3 / Senior / null / null
So now when I want to insert a group_id I will use this 3 ID's that I just created with NULL user_id and group_id.
My records will look something like this:
id / name / user_id / group_id
4 / NULL / 125 / 1 -> The id of the Junior group that is in the same table.
5 / NULL / 125 / 3 -> The id of the Senior group that is in the same table.
Is this a valid way to do it? How wrong it is?

Answer 1

I would recommend following the correct procedures as follows:
Table 1 users table:
id | name
Table 2 groups table:
id | name
Table 3 group_user pivot table:
id | user_id | group_id
Note: Table 3 should never hold a nullable value
The relation would be as follows, right now we have two models, a User model and a Group model.
both will have a belongsToMany relation towards each other.
Here is the method you will use in the User model:
public function groups()
{
$this->belongsToMany(User::class);
}
And here is the method you will use in the Group model:
public function users()
{
$this->belongsToMany(Group::class);
}
This is the recommended way to continue.