Question

I’m having a little trouble with a query I’ve written (please see below).

<?php 
require("phpfile.php"); 

// Start XML file, create parent node 

$dom = new DOMDocument("1.0"); 
$node = $dom->createElement("markers"); 
$parnode = $dom->appendChild($node); 

// Opens a connection to a MySQL server 

$connection=mysql_connect ("hostname", $username, $password); 
if (!$connection) { die('Not connected : ' . mysql_error());} 

// Set the active MySQL database 

$db_selected = mysql_select_db($database, $connection); 
if (!$db_selected) { 
die ('Can\'t use db : ' . mysql_error()); 
} 

$query = "SELECT userdetails.userid
                 , detectinglocations.locationid
                 , detectinglocations.locationname
                 , finds.findid
                 , finds.locationid
                 , finds.findosgb36lat
                 , finds.findosgb36lon
                 , finds.dateoftrip
                 , finds.findcategory
                 , finds.findname
                 ,finds.finddescription
                 , finds.detectorsettings
                 , finds.pasref
                 , finds.additionalcomments
                 , detectors.detectorname
                 , searchheads.searchheadname 
          FROM userdetails, detectinglocations, finds, detectors, searchheads 
          WHERE finds.userid=userdetails.userid 
            AND finds.locationid=detectinglocations.locationid 
            AND finds.detectorid=detectors.detectorid 
            AND searchheads.detectorid=detectors.detectorid"; 

$result = mysql_query($query); 
if (!$result) { 
die('Invalid query: ' . mysql_error()); 
} 

header("Content-type: text/xml"); 

// Iterate through the rows, adding XML nodes for each 

while ($row = @mysql_fetch_assoc($result)){ 
// ADD TO XML DOCUMENT NODE 
$node = $dom->createElement("marker"); 
$newnode = $parnode->appendChild($node); 
$newnode->setAttribute("findid",$row['findid']); 
$newnode->setAttribute("locationid",$row['locationid']); 
$newnode->setAttribute("locationname",$row['locationname']); 
$newnode->setAttribute("dateoftrip",$row['dateoftrip']); 
$newnode->setAttribute("findcategory",$row['findcategory']); 
$newnode->setAttribute("findname",$row['findname']); 
$newnode->setAttribute("finddescription",$row['finddescription']); 
$newnode->setAttribute("detectorname",$row['detectorname']); 
$newnode->setAttribute("searchheadname",$row['searchheadname']); 
$newnode->setAttribute("detectorsettings",$row['detectorsettings']);
$newnode->setAttribute("pasref",$row['pasref']);
$newnode->setAttribute("additionalcomments",$row['additionalcomments']);
} 

echo $dom->saveXML(); 

?>

When I run the php script through my web browser it retrieves the correct data, but when I run this through the HTML page I get an ‘Out of Stack’ error. From what I’ve read on the web, I think it may be because the SQL query is too complex.

Could you tell me please can an overly complex SQL query cause this type of error?

Answer 1

There’s something wrong/unexpected with your data.

1) Do a file_put_contents(“somedumpfile”, var_export($row, true)) at the top of each loop, and see what’s in the file after the process dies.
2) If that didn’t help, then systematically remove one field at a time from being added as a node, from top to bottom. When you stop getting the error, you found the culprit.
3) If that still didn’t help, start re-adding the fields as nodes, from top to bottom.

Make sure the PHP error-log is fully enabled and see if PHP is complaining about anything else. Also think about dumping the row index and PHP’s current memory consumption (memory_get_usage) into that same file.

Good luck. Share your results.

(Vote me up if you like/accept this answer.)

Dustin