$userCnt     = User::where("id",1)->count();
if( $userCnt ==0 ){
     //////////record not exists 
}else{
      //////////record exists 
}

注:其中条件根据您的要求。

如果你想插入一个唯一的记录，你可以使用laravel验证:

$validated = $request->validate([
    'title' => 'required|unique:usersTable,emailAddress|max:255',
]);

但是你也可以用这些方法:

1:

if (User::where('email',  $request->email)->exists())
{
  // object exists
} else {
  // object not found
}

2:

$user = User::where('email',  $request->email)->first();

if ($user)
{
  // object exists
} else {
  // object not found
}

3:

$user = User::where('email',  $request->email)->first();

if ($user->isNotEmpty())
{
  // object exists
} else {
  // object not found
}

4:

$user = User::where('email',  $request->email)->firstOrCreate([
      'email' => 'email'
],$request->all());

if($user->isEmpty()){
    // has no records
}

Eloquent使用集合。 参见以下链接:https://laravel.com/docs/5.4/eloquent-collections

在laravel雄辩中，有默认的exists()方法，参考下面的例子。

if (User::where('id', $user_id )->exists()) {
    // your code...
}

if ($u = User::where('email', '=', $value)->first())
{
   // do something with $u
   return 'exists';
} else {
  return 'nope';
}

可以用try/catch吗

->get()仍然返回一个空数组

这取决于您是想在之后使用用户，还是只检查是否存在一个用户。

如果用户对象存在，你想使用它:

$user = User::where('email', '=', Input::get('email'))->first();
if ($user === null) {
   // user doesn't exist
}

如果你只是想检查一下

if (User::where('email', '=', Input::get('email'))->count() > 0) {
   // user found
}

或者更好

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