how to make a custom validation rule in laravel with checking the value in Database code example

Example 1: custom rule laravel validation

public function store()
{
    $this->validate(request(), [
        'song' => [function ($attribute, $value, $fail) {
            if ($value <= 10) {
                $fail(':attribute needs more cowbell!');
            }
        }]
    ]);
}

Example 2: laravel request validation rules for create and update

public function rules()
    {
        $rules = [
            'name' => 'required|string|unique:products|max:255',
        ];

        if (in_array($this->method(), ['PUT', 'PATCH'])) {
            $product = $this->route()->parameter('product');

            $rules['name'] = [
                'required',
                'string',
                'max:255',
                Rule::unique('loan_products')->ignore($product),
            ];
        }

        return $rules;
    }