laravel where has query code example

Example 1: join in laravel eloquent

$customer = DB::table('customers')
                ->join('shops', 'customers.shop_id', '=', 'shops.shop_id')
                ->where('customer_contact', $contact_no)
                ->get();

Example 2: one to many laravel

For example, a blog post may have an infinite number of comments. And a single
comment belongs to only a single post  

class Post extends Model
{
    public function comments()
    {
        return $this->hasMany('App\Models\Comment');
    }
}

class Comment extends Model
{
    public function post()
    {
        return $this->belongsTo('App\Models\Post');
    }
}