PHP OOP Pagination - php

Question

I'm having an issue with pagination. I've debugged as mush as I can and it seems there is an issue with the SELECT query and execution. If I take out the pagination part the query executes and displays all entries in a long table. I tried executing an array, bindValue and bindParam but nothing works, can anyone see what I'm missing?
function showEmployees() {
$count = $this->dbh->query("SELECT * FROM employee_info");
$count->rowCount();
$count = $count->rowCount();
// if ($count > 0) {
// echo "The total amount of employees is " . $count;
// } else {
// echo "There are no records in this table.";
// }
$page_rows = 10;
$last_page = ceil($count / $page_rows);
echo $last_page;
if ($last_page < 1) {
$last_page = 1;
}
$page_num = 10;
if (isset($_GET['pn'])) {
$page_num = preg_replace('#[^0-9]#', '', $_GET['pn']);
}
if ($page_num < 1) {
$page_num = 1;
} elseif ($page_num > $last_page) {
$page_num = $last_page;
}
$limit = 'LIMIT ' .($page_num -1) * $page_rows .', '. $page_rows;
$query = $this->dbh->prepare("SELECT * FROM employee_info ORDER BY employee_id DESC :page_limit");
$query->bindParam(':page_limit', $limit );
$query->execute();
$t = "<table name='displayEmployees' border='1' >";
$t .="<tr>";
$t .= "<th>Employee ID</th>";
$t .= "<th>First Name</th>";
$t .= "<th>Last Name</th>";
$t .= "</tr>";
while($u = $query->fetch(PDO::FETCH_ASSOC)) {
$t .="<tr>";
$t .= "<td>{$u['employee_id']}</td>";
$t .= "<td>{$u['first_name']}</td>";
$t .= "<td>{$u['last_name']}</td>";
$t .="</tr>";
}
$t .="</table>";
return $t;
}

Answer 1

It think it's the way you handled the limit although that should have tripped an error.
Try:
$beginLimit = ($page_num-1)*$page_rows;
$endLimit = $page_rows;
$query = $this->dbh->prepare("SELECT * FROM employee_info ORDER BY employee_id DESC LIMIT :begin,:end");
$query->bindValue(':begin',(int)$beginLimit,PDO::PARAM_INT);
$query->bindValue(':end',(int)$endLimit,PDO::PARAM_INT);
$query->execute();

Answer 2

You can't include keywords as parameters to your prepared statements. You'll need to do this:
$limit = 'LIMIT ' .($page_num -1) * $page_rows .', '. $page_rows;
$query = "SELECT * FROM employee_info ORDER BY employee_id DESC ".$limit;
$query->query($query);
Note: because the parameters are already sanitised by your script you can trust them, so the benefit of a prepared statement is largely lost in this case.