PHP: How to check if no rows are returned

Question

With the following PHP code, how do i check if there's no row retuned so i can echo some message?

PHP:

<?php 
    require_once 'db_conx.php';
    $Result = mysql_query("SELECT * FROM ads WHERE pid = '2'")
        or die (mysql_error());
    while($row = mysql_fetch_array($Result)){
        echo '<span class="classPid" style="display:none">'.$row['pid'].'</span>';
    }
?>

Thanks

Answer 1

Something like this

<?php 
    require_once 'db_conx.php';
    $Result = mysql_query("SELECT * FROM ads WHERE pid = '2'")
        or die (mysql_error());
    $i=0;
    while($row = mysql_fetch_array($Result)){
        echo "<span class='classPid' style='display:none'>".$row['pid']."</span>";
        $i++;
    }
    if($i==0){
        echo "No rows found";
    }
?>