<?php

    if(isset($_POST["register"])){

    if(!empty($_POST['full_name']) && !empty($_POST['email']) && !empty($_POST['username']) && !empty($_POST['password'])) {
  $full_name= htmlspecialchars($_POST['full_name']);
    $email=htmlspecialchars($_POST['email']);
 $username=htmlspecialchars($_POST['username']);
 $password=htmlspecialchars($_POST['password']);
 $query=mysql_query("SELECT * FROM usertbl WHEREusername='".$username."'");
  $numrows=mysql_num_rows($query);
if($numrows==0)
   {
    $sql="INSERT INTO usertbl
  (full_name, email, username,password)
    VALUES('$full_name','$email', '$username', '$password')";
  $result=mysql_query($sql);
 if($result){
    $message = "Account Successfully Created";
} else {
 $message = "Failed to insert data information!";
  }
    } else {
    $message = "That username already exists! Please try another one!";
   }
    } else {
    $message = "All fields are required!";
    }
    }
    ?>

    <?php if (!empty($message)) {echo "<p class=\"error\">" . "MESSAGE: ". $message . "</p>";} ?>