how to save many foreign key at one cell

Question

i have two tables on mysql

Item Table

Id	item_name	room_id	other column
1	table	1
2	book	2
3	clock	2

Room Table

id	room_name
1	Teacher room
2	class room

I have a case that one item can be in several rooms,

I was asked for the data not to be duplicated as follows

Id	item_name	room_id	other column
1	table	1
2	table	2

how to store at one row column room_id has many value like this

Id	item_name	room_id	other column
1	table	1,2

I've done it using a string and then I extracted it using explode() but in mysql table I can't connect to the room table anymore

Answer 1

you can achieve that by using a pivot table

table: item_room

columns: item_id, room_id

models should look like this

namespace App\Models;

class Item extends Model
{
    public function rooms()
    {
        return $this->belongsToMany(Room::class)->using(ItemRoom::class);
    }
}

namespace App\Models;

class Room extends Model
{
    public function items()
    {
        return $this->belongsToMany(Item::class)->using(ItemRoom::class);
    }
}

namespace App\Models;

class ItemRoom extends Pivot
{
    
}

# you can get data using eager loading, quering relation, etc.
$room = Room::find(1);
foreach($room->items() as $items){
    //todo
}

$item = Item::find(1);
foreach($item->rooms() as $items){
   //todo
}