if (count($_POST)) {
    $email = $dbl->real_escape_string(trim(strip_tags($_POST['email'])));
    $passwd = $dbl->real_escape_string(trim(strip_tags($_POST['passwd'])));

    $query = "SELECT `email` FROM `tblUser` WHERE `email` = '$email'";
    $result = mysqli_query($dbl,$query);
    if(is_resource($result) && mysqli_num_rows($result) == 1 ){
            $row = mysqli_fetch_assoc($result);
            echo $email . " email exists " .  $row["email"] . "n";
    }
    else{
            echo "email no longer exists" . $email . "n";
    }
}

$query = mysqli_query($con, "SELECT * FROM emails WHERE email='".$email."'");

if(mysqli_num_rows($query) > 0){

    echo "email already exists";
}else{
    // do something
    if (!mysqli_query($con,$query))
    {
        die('Error: ' . mysqli_error($con));
    }
}

$query = mysqli_query($dbl, "SELECT * FROM `tblUser` WHERE email='".$email."'");

if(mysqli_num_rows($query) > 0){

    echo "email already exists";
}else{
    // do something
    if (!mysqli_query($dbl,$query))
    {
        die('Error: ' . mysqli_error($dbl));
    }
}

$query = "SELECT `email` FROM `tblUser` WHERE email=?";

if ($stmt = $dbl->prepare($query)){

        $stmt->bind_param("s", $email);

        if($stmt->execute()){
            $stmt->store_result();

            $email_check= "";
            $stmt->bind_result($email_check);
            $stmt->fetch();

            if ($stmt->num_rows == 1){

            echo "That Email already exists.";
            exit;

            }
        }
    }

<?php
$email = $_POST['email'];

$mysql_hostname = 'xxx';
$mysql_username = 'xxx';
$mysql_password = 'xxx';
$mysql_dbname = 'xxx';

try {
$conn= new PDO("mysql:host=$mysql_hostname;dbname=$mysql_dbname", $mysql_username, $mysql_password);
     $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
} catch (PDOException $e) {
     exit( $e->getMessage() );
}

// assuming a named submit button
if(isset($_POST['submit']))
    {

        try {
            $stmt = $conn->prepare('SELECT `email` FROM `tblUser` WHERE email = ?');
            $stmt->bindParam(1, $_POST['email']);
            $stmt->execute();
            while($row = $stmt->fetch(PDO::FETCH_ASSOC)) {

            }
        }
        catch(PDOException $e) {
            echo 'ERROR: ' . $e->getMessage();
        }

    if($stmt->rowCount() > 0){
        echo "The record exists!";
    } else {
        echo "The record is non-existant.";
    }


    }
?>

$query = "SELECT `email` FROM `tblUser` WHERE `email` = '$email'";
$result = mysqli_query($link,$query); //$link is the connection

if(mysqli_num_rows($result) > 0 ){....}

if(is_resource($query) && mysqli_num_rows($query) > 0 ){
        $query = mysqli_fetch_assoc($query);
        echo $email . " email exists " .  $query["email"] . "n";

if(is_resource($result) && mysqli_num_rows($result) == 1 ){
        $row = mysqli_fetch_assoc($result);
         echo $email . " email exists " .  $row["email"] . "n";

SELECT IF( EXISTS (
                  SELECT *
                  FROM `Table`
                  WHERE `email` = @Email)
          , 1, 0) as `Exist`

$query = Call MYSQL_SP($EMAIL);
 $result = mysqli_query($conn,$query);
 $row = mysqli_fetch_array($result)
 $exist = ($row['Exist']==1)? 'the email exist' : 'the email doesnt exist';

//check if username already exists
       include 'phpscript/connect.php'; //connect to your database

       $sql = "SELECT username FROM users WHERE username = '$username'";
       $result = $conn->query($sql);

       if($result->num_rows > 0) {
           $usernameErr =  "username already taken"; //takes'em back to form
       } else { // go on to INSERT new record