laravel中查询的结果为二维数组
$userInfo = DB::table("admin") ->where("username",$username) ->where("password",$pass) ->get() ->map(function ($value) { return (array)$value; })->toArray();
$userInfo = DB::table("admin") ->where("username",$username) ->where("password",$pass) ->get() ->map(function ($value) { return (array)$value; })->toArray();