need help w/date compare

[12Strings]

Hi, I just want to update a database
table column (datepaid-type is DATE(YYYY-MM-DD) to the current date
IF the duedate >= the current date, payrec = 'P', status = 'Y'and datepaid is ' '. I appreciate that my coding is dismal, sorry. Any help?

[B]<?php   
    $hostname = "localhost";
    $database = "homedb";
    $username = "root";
    $password = "cookie";
 try
 {
$dbconn = new PDO("mysql:host=$hostname;dbname=$database", $username, 

$password);
        $dbconn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
        $dbconn->exec('SET NAMES "utf8"');
 }
 catch (PDOException $e)
 {
        $error = "Unable to connect to the database server.";
        // Display error to user
        exit();
 }
$acctno="accto"; $payrec="payrec"; $status="status";
$duedate="duedate"; $datepaid="datepaid";
if($duedate == 'CURDATE')
try
 {
        $query = $dbconn->prepare("
            UPDATE testbl SET $datepaid = CURDATE()
            WHERE 
                payrec = 'P' AND status = 'Y' AND datepaid IS NULL
        ");
$query->execute(array(
            ":acctno" => $_POST['acctno'],
            ":payrec" => $_POST['payrec'],
            ":status" => $_POST['status'],
            ":duedate" => $_POST["duedate"],
            ":datepaid" => $_POST["datepaid"]
        ));
 }
catch(PDOException $e)
 {
        $error = "Error retrieving user: ".$e->getMessage();
        // Display error to user
        exit();
 }
?>[/B]

[12Strings]

Hi, I have checked the validity of the table and in
all 3 records "recur" ='Y', "payrec" ='p', values are in "duedate",
"datepaid" (type is DATE) and "periodic". I'm looping thru the data; var_dump() displays NULL NULL NULL, It seems that my DATEDIFF is flawed.
I've spent considerable time viewing forums, manuals, code types. How about some advice?

<?php
error_reporting(E_ALL ^ E_NOTICE);
// error_reporting(0);
$servername = "localhost"; $username = "root";
$password = "cookie"; $dbname = "test";

// Create connection
$conn = new mysqli($servername, $username, $password, $dbname);
// Check connection
if ($conn->connect_error)
   { die("Connection failed: " . $conn->connect_error); }
// ==================================================
$sql = "SELECT recur, periodic, pd, payrec, duedate, datepaid,
DATEDIFF(CURDATE(),duedate) AS dayslate
FROM testbl WHERE recur = 'Y' && payrec = 'P'";
$result = $conn->query($sql);
if ($result->num_rows > 0)
 {
    // output data of each row
    while($row = $result->fetch_assoc()) // ****3 records *****
 {
    // ***************************************************
    var_dump($dayslate); // NULL NULL NULL 
   // ***************************************************
    if ($dayslate > 0)
 { 
    if($dayslate > 120)
    {$pastdue = "PAST DUE";}

    if($periodic == 1)
           { $duedate = date('Y-m-d', strtotime('+4 week')) ."\n"; }
    if($periodic == 6)
           { $duedate = date('Y-m-d', strtotime('+25 week')) ."\n"; }
$pd = 'P'; $daylate = 0;
// ==================================================
$sql = "UPDATE testbl SET
        pd = '$pd',
   duedate = '$duedate',                      
 $datepaid = 'NOW()',
  dayslate = '$dayslate'
 WHERE dayslate = 0";
if ($conn->query($sql) === TRUE)
    { echo "Record updated successfully"; } 
    else
    { echo "Error updating record: " . $conn->error; }

$conn->close(); 
 }
  }
 }
 // header( "refresh:3;url='http://localhost/invoice/autolist.php'");
?>