Here is an example of the code I've tried - as recommended from several searches...
code working in directory:
http://localhost:8000/cc/fleetadmin/

//get blob (logo)
$sql = "SELECT logo FROM files WHERE fleetnumber='$fleetnumber'";
$query_results = mysql_query($link, $sql);
header("Content-type: image/png");
echo '<img src="'.mysql_result($query_results, 0).'">';

I stored a .png in the variable logo in table 'files'
I get the message "the image "http:///localhost:8000/cc/fleetadmin/" cannot be displayed because it contains errors

<<< that's a PHP message - does it contain a clue to what I'm missing??? I've tried with mysqli_query & mysqli_result - same thing