Jquery ajax没有向数据库提交表单

Question

我的jquery ajax没有将表单提交到我的php文件。成功警报仅在提交时警告空白，并且不会向我的数据库插入任何内容。但我的php文件在不使用ajax的情况下插入数据库。

这是我的代码，任何想法或新方法

这是AJAX代码

    $(document).ready(function(){
          alert("mannn");
          $("#adduser").submit(function(){
            $.ajax({
              type: "POST",
              url: "adduser_processor.php",
              data: $('#adduser').serialize(),
              success: function(data){
                alert(data);
              }

这是要插入数据库的php代码

if (isset($_POST['submit'])) {
  //Check if the form is submitted
  $fullname = $_POST['fullname'];
  $username = $_POST['username'];
  $gender = $_POST['gender'];
  $about = $_POST['about'];
  $number = $_POST['number'];
  $password = $_POST['password'];
  $timeadded = date("Y/m/d, \a\\t G.ia ( l)");
  $address = $_POST['address'];
  // Wanna Clean Values to prevent fro Hackers

  $fullname = cleaninputs($fullname);
  $username = cleaninputs($username);
  $about = cleaninputs($about);
  $number = cleaninputs($number);
  $gender = cleaninputs($gender);
  $password = cleaninputs($password);
  $address = cleaninputs($address);

  $checkuserq = "SELECT username FROM pos_staffs WHERE username = '$username'";
  $exeq = mysqli_query($connection, $checkuserq);
  $numrow = mysqli_num_rows($exeq);
  if ($numrow > 0) {
    $msg = "<li class='list-group-item list-group-item-danger'>Username ($username) Choosen by Another Staff</li>";
    //echo $msg;
    //header("location:addnewuser.php?msg=$msg");
  } else {
      $insertquery = "INSERT INTO pos_staffs(id,fullname,username,password,about,gender,address,date_joined)
      VALUES('','$fullname','$username','$password','$about','$gender','$address','$timeadded')";
      $insertq = mysqli_query($connection, $insertquery);
      if ($insertq) {
        //header("location:addnewuser.php?msg=$msg");
        $msg = "New Staff ($fullname) has being added he can now Login";
        echo $msg;
      } else {
        $msg = "Something Went Wrong";
        echo $msg;
      }

但是我不认为我的php文件有错误，因为它正常插入而没有错误。