Here i am populating my dropdowns with database fields using php my code follows,
while ($row = mysql_fetch_array($result)) {
$series1 .= "<option id='Series1' value='" . $row['Series'] ."'>" . $row['Series'] ." </option>";
}
after fetching i echo it to html
<select id="Series1" onchange="changeVal('Series1')">
<option value="">Please select</option>
<?php echo $series1 ?>
</select>
my problem is i have some null values in the database field, i don't want that to be inserted in the options field. my final result now look like this

please help me.
WHERE col IS NOT NULLin the where clause