Linux, Apache, MySQL, PHP

$dbh = new PDO('mysql:host='.$hostname.';dbname='.$dbname,$username, $password);

Fatal error: Class 'PDO' not found

RewriteRule ^(php)($|/) - [L]

@font-face {font-family: "Kufi"; src: url('font/DroidKufi-Regular.ttf') ;}

if ($_POST['cboIndustry'])
{
    foreach ( $_POST['cboIndustry'] as $key => $value )
    {
        $mysql_query = $mysql_connection->prepare('CALL sp_add_new_company_industry(:param_member_guid, :param_company_guid, :param_company_industry, :param_created_ip_address)');
        $mysql_query->bindParam(':param_member_guid', $_SESSION["xoompage_member_guid"], PDO::PARAM_STR);
        $mysql_query->bindParam(':param_company_guid', $company_guid, PDO::PARAM_STR);
        $mysql_query->bindParam(':param_company_industry', $value, PDO::PARAM_STR);
        $mysql_query->bindParam(':param_created_ip_address', $_SERVER['REMOTE_ADDR'], PDO::PARAM_STR);
        $mysql_query->execute();
    }
}

PDO Exception Caught. Error with the database: 
SQL Query: Code: HY000 Error: SQLSTATE[HY000]: General error: 1366 Incorrect integer value: '' for column 'param_company_industry' at row 1SQLSTATE[HY000]: General error: 1366 Incorrect integer value: '' for column 'param_company_industry' at row 1

array(1) { [0]=> string(0) "" } 

<tr>
    <td valign="middle">Industry</td>
    <td valign="middle">:</td>
    <td valign="middle">         
        <div id="container">
        <select id="cboIndustry" name="cboIndustry[]" style="width: 80%" <?php if (!$_GET["id"]) { ?>required<?php } ?>>
            <option value="" selected>[Industry..]</option>
            <?php
                $mysql_command = "CALL sp_populate_industry()";
                $mysql_query = $mysql_connection->prepare($mysql_command);

                $mysql_query->execute();

                while($mysql_row = $mysql_query->fetch())
                {
            ?>
            <option value="<?php echo $mysql_row['industry_id']; ?>"><?php echo $mysql_row['industry_name']; ?></option>
            <?php } ?>
        </select>
        <button id="btnAddIndustry" type="button" style="width:150px">Add More</button>
        </div>
    </td>
</tr>

<video loop="loop" autoplay="autoplay" preload="none">

<source  src="video/video1.mp4" type="video/mp4"></source>
</video>

<?php if (!isset($company_region) || !empty($company_region) || !is_null($company_region)) { ?>
<tr>
    <td align="left" valign="top" style="width: 100px;">State / City</td>
    <td align="center" valign="top" style="width: 20px;">:</td>
    <td align="left" valign="top"><?php echo $company_region; ?></td>
</tr>
<?php } ?>