Trying to get Unique entries set right for my form - php

Question

so I have searched this problem and found similar ones, but I'm not sure of how to translate their solutions into mine - mainly because I'm a noob in PHP. I'm working on it. Bear with me. I appreciate the help!
Right now, I am trying to make it so my form will not allow duplicate entries for the email column in phpmysql. So far, I went into the structure tab there, and made it unique. Pretty much viola. However, I would like the error message to display on the same page when the form is submitted, instead of reloading it and giving the message. Also, I would like to customize the message. Seeing as its a phpmysql related error, I'm not sure if I would do that with PHP coding, or somewhere in there.
Thanks guys. I appreciate the help.
<?php
function checkField($v){
return (isset($v) && $v === false) ? true: false;
}
function startMysql(){
$con=mysqli_connect("localhost", "shiftedr_admin", "passwerd", "shiftedr_whosthedeeusers");
// Check connection
if (mysqli_connect_errno()){
echo "Failed to connect to MySQL: " . mysqli_connect_error();
} else {
return null;
}
return $con;
}
// function closeMySql($connection){
// mysqli_close($connection);
// }
function formcheck(){
$con=mysqli_connect("localhost", "shiftedr_admin", "shithead1", "shiftedr_whosthedeeusers");
// Check connection
if (mysqli_connect_errno()){
echo "Failed to connect to MySQL: " . mysqli_connect_error();
} else {
if (isset($_POST['submitted'])){
$form = null;
if (empty($_POST['fullname'])){
$form['fullnameflag'] = false;
}
if (empty($_POST['email'])){
$form['emailflag'] = false;
}
if (empty($_POST['password'])){
$form['passwordflag'] = false;
}
if (empty($_POST['pwc'])){
$form['pwcflag'] = false;
}
if (empty($_POST['userbday'])){
$form['userbday'] = false;
}
if (empty($_POST['gender'])){
$form['genderflag'] = false;
}
if ($_POST['password'] != $_POST['pwc']){
$form['fixpasswordconfirm'] = false;
}
/*$query = mysql_query ("SELECT * FROM users2 WHERE email = '". Email'" ."'");
if (mysql_num_rows($query) > 0)
{
echo 'Email Address is Already In Use.';
}*/
if (empty($form)) { // all fields correct at this point, do database stuff
$sql="INSERT INTO Users2 (fullname, Email, Password, userbday, Gender) VALUES ('".$_POST['fullname']."','".$_POST['email']."','".$_POST['password']."','".$_POST['userbday']."','".$_POST['gender']."')";
if (!mysqli_query($con,$sql)){
die('Error: ' . mysqli_error($con));
}
echo "1 record added";
}
}
mysqli_close($con);
return $form;
}
}
//// / include("myfunctions.php");
?>

Answer 1

I am guessing you have two pages - myform.php and process.php or something similar so try doing this
<?php
$error = null;
if( isset( $_POST['submitted'] ) ) // Same as your check is submitting if
{
// Below is an example fail
if( empty( $_POST['fullname'] ) ) $error = 1;
// So for the email address failing you would put
if( mysql_num_rows($query) > 0 ) $error = 2;
if(! $error )
{
// all good no errors here so do database stuff....
}
else
{
header("Location: form.php?error=$error"); // return the error code to previous page
}
}
?>
Were one could be an empty field or could be fullname is empty and two is used email address or something similar and on your myform.php page have
<?php
if( isset( $_GET['error'] ) )
{
switch ( $_GET['error'] )
{
case 1 : echo "One of the fields is empty"; break;
case 2 : echo "Your email address has already been used"; break;
default : echo "Unknown error occured";
}
}
?>