SQL UPDATE with CONCAT

programming
1

I’m trying to split a file with PHP and put it into a LONGBLOB in chunks.

Is there some kind of mysql limit? (the chunking should get past the max_allowable_packet problem)

For some reason it doesn’t work with files in the larger range (10MB or more approximately)

What should I do!?

$docdata = $_FILES['docdata']['tmp_name'];
$docsize = filesize($docdata);
$data = addslashes(fread(fopen($docdata, "r"), filesize($docdata))); //<- RAW DATA

    $oneMeg = 1040000; //roughly
    if ($docsize > $oneMeg) {
        $numMegs = ceil($docsize/$oneMeg); //the uppermost number of megs in this file
        $numChars = strlen($data); //the number of characters in the data string
        $len = floor($numChars/$numMegs); //how many characters per section
        $fd_temp = $data; //placeholder
        
        $i = 0;
        while (strlen($fd_temp) > 0) {
            $section[$i] = substr($fd_temp, 0, $len); //takes the first LEN characters
            $fd_temp = substr($fd_temp, $len); //shortens it by LEN characters for next loop
            $i++; //increment the array index
        }
        $query ="INSERT INTO `documents` (`docname`,`docclass`,`doctype`,`docdata`,`docsize`) VALUES ('$docname','$docclass','$doctype','$section[0]','$docsize')"; //$docname $docclass $doctype are defined earlier
        
        $result = mysql_query($query);
        $theID = mysql_insert_id();
        if (!$result) {
            $err[] = "Error: the first part of the file could not be inserted";
        }
        else if (!$theID) {
            $err[] = "Error: the last insert ID could not be retrieved.";
        }
        else { //only run the next parts if the first part went in OK
            for ($i = 1; $i < count($section); $i++) {

$query = "UPDATE `documents` SET `docdata`=CONCAT(`docdata`,'$section[$i]') WHERE `docid`=$theID";
                $result = mysql_query($query);

                if (!$result) {
                    $err[] = "Error inserting a part of the file. Please delete the incomplete file and try again.";
                    break;
                }//end if
            }//end for
        }//end else
    }//end for large files

Thanks so much in advance… Even if you don’t know what’s wrong, but made it this far, I appreciate your effort.
-Karl