简单，舒适和易于理解的Validator

class CustomerController extends Controller
{
    public function register(Request $request)
    {

        $validator = Validator::make($request->all(), [
            'name' => 'required|string|max:255',
            'email' => 'required|string|email|max:255|unique:customers',
            'phone' => 'required|string|max:255|unique:customers',
            'password' => 'required|string|min:6|confirmed',
        ]);

        if ($validator->fails()) {
            return response(['errors' => $validator->errors()->all()], 422);
        }

这是一个简单的代码来检查电子邮件是否存在数据库

    $data = $request->all();
    $user = DB::table('User')->pluck('email')->toArray();
    if(in_array($user,$data['email']))
    {
    echo 'existed email';
    }

这将检查用户表中是否存在所请求的电子邮件:

if (User::where('email', $request->email)->exists()) {
   //email exists in user table
}

Laravel 6或顶部:写表名，然后给出where子句条件，例如where('id'， $request->id)

 public function store(Request $request)
    {

        $target = DB:: table('categories')
                ->where('title', $request->name)
                ->get()->first();
        if ($target === null) { // do what ever you need to do
            $cat = new Category();
            $cat->title = $request->input('name');
            $cat->parent_id = $request->input('parent_id');
            $cat->user_id=auth()->user()->id;
            $cat->save();
            return redirect(route('cats.app'))->with('success', 'App created successfully.');

        }else{ // match found 
            return redirect(route('cats.app'))->with('error', 'App already exists.');
        }

    }

if (User::where('email', Input::get('email'))->exists()) {
    // exists
}

最好的解决方案之一是使用firstOrNew或firstOrCreate方法。文档中有更多关于这两者的详细信息。