php - Registration form update to MySQL PDO -

i'm new php , mysql. have following registration form asks user put in name, password , email. validation works , i'm able connect database cannot insert table because i'm having hard time updating code old mysql mysql pdo. here code:

form:

<form name="registration" method="post" action="registration.php">     <table width="400" border="5" align="center">     <tr>       <td colspan="5"><h1>registration form</h1></td>     </tr>     <tr>       <td>user name:</td>       <td><input type="text" name="name" /></td>     </tr>     <tr>       <td>user password:</td>       <td><input type="password" name="pass" /></td>     </tr>     <tr>       <td>user email:</td>       <td><input type="text" name="email" /></td>     </tr>     <tr>       <td colspan="5" align="center"><input type="submit" name="submit" value="sign up" /></td>     </tr>     </table> </form> 

here php , mysql part:

<?php // pdo connect $servername = "localhost"; $username = "root"; $password = ""; $dbname = "users_db";  try {     $conn = new pdo("mysql:host=$servername;dbname=$dbname", $username, $password);     // set pdo error mode exception     $conn->setattribute(pdo::attr_errmode, pdo::errmode_exception);     //echo "connected successfully";     } catch(pdoexception $e)     {     echo "connection failed: " . $e->getmessage();     }       if(isset($_post['submit'])){      $user_name = $_post['name'];     $user_pass = $_post['pass'];     $user_email = $_post['email'];          if($user_name==''){         echo "<script>alert('please enter name!')</script>";         exit();         }          if($user_name==''){         echo "<script>alert('please enter password!')</script>";         exit();         }          if($user_name==''){         echo "<script>alert('please enter email!')</script>";         exit();         }       // validation , field insertion      $check_email = "select * users user_name='$user_email'";      $run = mysql_query($check_email);      if(mysql_num_rows($run)>0){         echo <script>alert('email $user_email exist!')</script>";         exit();     }      $query = "insert users(user_name,user_pass,user_email) values ('$user_name','$user_name','$user_name') ";     if(mysql_query($query)){         echo <script>window.open('welcome.php','_self')</script>";         exit();     }      } ?> 

please let me know how can update after "// validation , field insertion" part.

its here need read more pdo:

<?php // pdo connect $servername = "localhost"; $username = "root"; $password = ""; $dbname = "users_db";  try {     $conn = new pdo("mysql:host=$servername;dbname=$dbname", $username, $password);     // set pdo error mode exception     $conn->setattribute(pdo::attr_errmode, pdo::errmode_exception);     //echo "connected successfully";     } catch(pdoexception $e)     {     echo "connection failed: " . $e->getmessage();     }       if(isset($_post['submit'])){      $user_name = $_post['name'];     $user_pass = $_post['pass'];     $user_email = $_post['email'];          if($user_name==''){         echo "<script>alert('please enter name!')</script>";         exit();         }          if($user_name==''){         echo "<script>alert('please enter password!')</script>";         exit();         }          if($user_name==''){         echo "<script>alert('please enter email!')</script>";         exit();         }       // validation , field insertion      $check_email = "select * users user_email = :email";     $check_email = $conn->prepare($check_email);     $check_email->execute(array(':email'=>$user_email));     if($check_email->rowcount() >0){         echo "<script>alert('email $user_email exist!')</script>";         exit();     }      $query = "insert users(user_name,user_pass,user_email) values (?, ?, ?)";     $query = $conn->prepare($query);     $query->bindparam('1', $user_name);     $query->bindparam('2', $user_pass);     $query->bindparam('3', $user_email);     $query->execute();     if($query->rowcount() > 0) {         echo "<script>window.open('welcome.php','_self')</script>";         exit();     }     } ?>