I want items to be under the category they are related to - laravel

Question

I want to achieve this result, but I can't understand the logic of the sql implementation
here is my welcome.blade.php:
#extends('layouts/layout')
#section('content')
<div class="container-fluid">
#foreach ($categories as $category)
<h4>{{$category->category_name}}</h4>
<div class="row">
<div class="col-sm-4">
<h6>{{$category->item_name}}</h6>
</div>
</div>
#endforeach
</div>
#endsection
and my controller:
$categories = DB::table('items')
->join('categories', 'items.category_id', 'categories.id')
->select('items.item_name', 'items.item_price', 'categories.category_name', 'categories.description')
->groupBy('categories.category_name')
->get();
return view('welcome', 'categories'=> $categories]);

Answer 1

You can use the QueryBuilder here if you want, but I would suggest using Eloquent unless you have a particular reason to not use it.
Let's assume that you have a Category and Item model and that you've defined a relational function within the Category model back to the Item model.
class Category extends Model
{
public function items()
{
// this assumes you're using standard naming conventions
return $this->hasMany(Item::class);
}
}
Then in your Controller, you might do something like the following to obtain categories and their related items.
$categories = Category::with('items')->get();
return view('welcome', compact('categories'));
The above can be adapted when required to limit the query to a specific Category when you require it. We use the with method to eager load the related records so that we can avoid the n+1 query problem.
Finally, in your view you can iterate (loop) over the categories and loop over the related items (there could be more than one).
#forelse($categories as $category)
<h4>{{ $category->category_name }}</h4>
#forelse ($category->items as $item)
<p>{{ $item->item_name }}</p>
#empty
<p>No items</p>
#endforelse
#empty
<p>No results</p>
#endforelse
The above is purely illustrative and ideally, you would break the above into reusable components.

Answer 2

Since you're using Laravel, you could use Eloquent relationships:
class Category extends Model{
public function items{
return $this->hasMany(Item::class);
}
}
Then in your controller:
$categories = Category::with('items')->get();
return view('welcome', ['categories'=> $categories]);
Then in your view:
#foreach ($categories as $category)
<h4>{{$category->category_name}}</h4>
#foreach($category->items as item)
<div class="row">
<div class="col-sm-4">
<h6>{{$item->name}}</h6>
</div>
</div>
#endforeach
#endforeach

Answer 3

$categories = DB::table("categories")->select("id", "category_name", "description")->get();
$items = DB::table("items")->select("category_id", "item_name", "price")->get();
view('welcome',compact("categories", "items"));
/////////////////////// BLADE ///////////////////////
<div class="container-fluid">
#foreach ($categories as $category)
#foreach($items as $item)
#if($category->id === $item->category_id)
<h4>{{$category->category_name}}</h4>
<div class="row">
<div class="col-sm-4">
<h6>{{$category->item_name}}</h6>
</div>
</div>
#endif
#endforeach
#endforeach
</div>
Try this.