Yes! That did it. I used a statement like this:
<?
$queryC = "SELECT IF(blobData IS NULL, 0, 1) as c1, IF(blobData2 IS NULL, 0, 1) as c2, IF(blobData3 IS NULL, 0, 1) as c3, IF(blobData4 IS NULL, 0, 1) as c4 FROM blobs WHERE blobId='$id' LIMIT 1";
$resultC = mysql_query($queryC) or...