rewrite queries from deprecated mysql_connect to PDO in PHP - php

Question

i am rewriting code mysql_connect deprecated below to work in PDO but cannot get it to work properly. no error is showed. i have tried everything I could. can someone help me
deprecated mysql_connect
<?php include('config.php'); ?>
<?php
if(isset($_POST['page'])):
$paged=$_POST['page'];
$sql="SELECT * FROM `users` where qualify='Po' ORDER BY `uid` desc ";
if($paged>0){
$page_limit=$resultsPerPage*($paged-1);
$pagination_sql=" LIMIT $page_limit, $resultsPerPage";
}
else{
$pagination_sql=" LIMIT 0 , $resultsPerPage";
}
$result=mysql_query($sql.$pagination_sql);
$num_rows = mysql_num_rows($result);
if($num_rows>0){
while($data=mysql_fetch_array($result)){
$userid=$data['uid'];
$fullname=$data['fullname'];
echo "<li><h3>$userid</h3><p>$fullname<p></li>";
}
}
if($num_rows == $resultsPerPage){?>
<li class="loadbutton"><button class="loadmore" data-page="<?php echo $paged+1 ;?>">Load More</button></li>
<?php
}else{
echo "<li class='loadbutton'><h3>No More Data</h3></li>";
}
endif;
?>
convert to PDO
<?php
$resultsPerPage=1;
$db = new PDO (
'mysql:host=localhost;dbname=chat;charset=utf8',
'root', // username
'' // password
);
?>
<?php include('pdo.php'); ?>
<?php
if(isset($_POST['page'])):
$paged=$_POST['page'];
$prefix = "";
//Loadmore configuarion
$resultsPerPage=1;
$sql = $db->prepare("SELECT * FROM users where qualify=:qualify ORDER BY uid desc");
$sql->execute(array(':qualify'=>'po'));
if($paged>0){
$page_limit=$resultsPerPage*($paged-1);
$pagination_sql=" LIMIT $page_limit, $resultsPerPage";
}
else{
$pagination_sql=" LIMIT 0 , $resultsPerPage";
}
$result = $db->prepare($sql.$pagination_sql);
$num_rows = $result->rowCount();
if($num_rows>0){
while ($row = $result->fetch()) {
$userid=htmlentities($row['uid'], ENT_QUOTES, "UTF-8");
$fullname=htmlentities($row['fullname'], ENT_QUOTES, "UTF-8");
echo "<li><h3>$userid</h3><p>$fullname<p></li>";
}
}
if($num_rows == $resultsPerPage){?>
<li class="loadbutton"><button class="loadmore" data-page="<?php echo $paged+1 ;?>">Load More</button></li>
<?php
}else{
echo "<li class='loadbutton'><h3>No More Data</h3></li>";
}
endif;
?>
Thank you so much

Answer 1

Your solution here is to look at http://php.net/manual/en/pdo.setattribute.php and put the following code after your PDO construct:
$db->setAttribute(PDO::ATTR_ERRMODE,PDO::ERRMODE_EXCEPTION);
This won't fix your code but it should show you why the error is occuring and you can debug it fully from there.