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i'am trying to insert data in database ..what is the problem inside  my code
this is my code
dbConnect.php
<?php

   class DB
{
    function __construct()
    {
        $conn = mysqli_connect('localhost','root','iws123#','register') or die('connection problem'.mysqli_error());


    }
    public function insert($username,$email,$password)
    {
    $re=mysqli_query($conn,"insert into table2(username,email,password) values('".$username."','".$email."','".$password."')");
    return $re;
    }
}
?>

index.php

<?php
 include('dbConnect.php');
ini_set('display_errors', 1);
ini_set('display_startup_errors', 1);
error_reporting(E_ALL);

$obj= new DB();//Creating object

if(isset($_Post['submit']))
{
    $username =$_Post['username'];
    $email    =$_Post['email'];
    $password =$_Post['password'];
    $confirmPassword = $_POST['confirm_password'];
      if($password == $confirmPassword)

        {

         $re=$obj->insert($username,$email,$password);


         if($re)
            {
             echo "<script>alert('data insert')</script>";
            }

        else
          {

             echo "<script>alert('data not insert')</script>";
           }
        }
        else
        {
            echo "<script>alert('Password Not Match')</script>";

        }
}
?>

<!DOCTYPE html>
<html lang="en">
<head>
<script type="text/javascript" src="jqy.js"></script>
<script type="text/javascript">
/*function myfunction(){
  alert("ok");
var email= $("#em1").val();
$.ajax({
    type:'post',
        url:'test3.php',
        data:{email: email},
        success:function(data){
          //alert(data);
          $('.emailid').html(data);
        }
 });
}*/

</script>
  </script>

  <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1.0, user-scalable=no">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <!-- CORE CSS-->

  <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/materialize/0.97.1/css/materialize.min.css">

<style type="text/css">
html,
body {
    height: 100%;
}
html {
    display: table;
    margin: auto;
}
body {
    display: table-cell;
    vertical-align: middle;
}
.margin {
  margin: 0 !important;
}
</style>

</head>

<body class="blue">


  <div id="login-page" class="row">
    <div class="col s12 z-depth-6 card-panel">
      <form  action="" class="login-form" method="post" >
        <div class="row">
          <div class="input-field col s12 center">
            <p class="center login-form-text">SignUp Form</p>
          </div>
        </div>
        <div class="row margin">
          <div class="input-field col s12">
            <i class="mdi-social-person-outline prefix"></i>
            <input id="username" type="text" name="username" class="validate" required/>
            <label for="username" class="center-align">Username</label>
          </div>
        </div>
        <div class="row margin">
          <div class="input-field col s12">
            <i class="mdi-communication-email prefix"></i>
            <input id="em1" type="email" name="email" class="validate" onblur="myfunction()" required/>
            <label for="em1" class="center-align">Email</label>
          </div>
        </div>
        <div class="row margin">
          <div class="input-field col s12">
            <i class="mdi-action-lock-outline prefix"></i>
            <input id="password" type="password" name="password" class="validate" required/>
            <label for="password">Password</label>
          </div>
        </div>
        <div class="row margin">
          <div class="input-field col s12">
            <i class="mdi-action-lock-outline prefix"></i>
            <input id="password-again" type="password" name="confirm_password" required/>
            <label for="password-again">Confirm password</label>
          </div>
        </div>
        <div class="row">
          <div class="input-field col s12">
            <input type="submit" name="submit" value="Register" />
          </div>
          <div class="input-field col s12">
            <p class="margin center medium-small sign-up">Already have an account? <a href="login.php">Login</a></p>
          </div>
        </div>
      </form>
    </div>
  </div>

  <!-- jQuery Library -->
 <script type="text/javascript" src="//ajax.googleapis.com/ajax/libs/jquery/1.11.2/jquery.min.js"></script>
  <!--materialize js-->
  <script src="https://cdnjs.cloudflare.com/ajax/libs/materialize/0.97.1/js/materialize.min.js"></script>


  <script>
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  })(window,document,'script','//www.google-analytics.com/analytics.js','ga');

  ga('create', 'UA-27820211-3', 'auto');
  ga('send', 'pageview');

</script><script src="//load.sumome.com/" data-sumo-site-id="1cf2c3d548b156a57050bff06ee37284c67d0884b086bebd8e957ca1c34e99a1" async="async"></script>


</body>

</html>