sql driver problem

Everything is fine but the Looping...

[Acolyte]

Hi All,

I've made my own database (MySQL) driver / layer. No problem so far till it comes to looping. At first all looks fine, but at the end my own error handler reports an error. There is no usefull information available (like what MySQL errorcode returned) only things that are logical. It seems that the loop loops one time too much. So if there are 8 rows in the result, he tries to get an 9th one. That one doesn't exists --> error.
I have really no idea what it could be. Here's the source code of my testfile:

<?php
include_once("../source/api.php");
$API = new API;
$testquery = "SELECT * FROM ".$API->pre."modinfo";
$p = $API->database->dbquery($testquery, 0, __LINE__, __FILE__);
while($res = $API->database->dbFetchQuery($p, __LINE__, __FILE__))
{
 echo "ID: <b>".$res[0]."</b><br />\n";
echo "mName: <b>".$res[1]."</b><br />\n";
 echo "mDesc: <b>".$res[2]."</b><br />\n";
echo "mImage: <b>".$res[3]."</b><br />\n";
 echo "mActive: <b>".$res[4]."</b><br />\n";
echo "mFN: <b>".$res[5]."</b><br />\n";
 echo "mCat: <b>".$res[6]."</b><br />\n";
echo "mShow: <b>".$res[7]."</b><br />\n";
echo "<br />\n";
}
?>

And the source codes of the used db-functions plus the error-handler I wrote:

<?php
function dbquery($query, $do_fetch = 1, $linenumber = 0, $file = "Not specified (dbquery)") {
// false and 0 are seen as the same in php. everything else will be seen as true
$the_query = mysql_query($query) or die($this->sqlFatalError($query, $linenumber, $file));
if($do_fetch == 1){
$this->queryCount++;
$this->arrayQueries[] = $query;
$result = mysql_fetch_row($the_query) or die($this->sqlFatalError($query, $linenumber, $file));
}
else {
$this->queryCount++;
$this->arrayQueries[] = $query;
$result = $the_query;
}
if(!$result){
die($this->sqlFatalError($query, $linenumber, $file));
}
return $result;
} 
function dbFetchQuery($query_to_fetch, $linenumber = 0, $file = "Not specified (fetch)")
{
if(!isset($query_to_fetch))
{
return;
}
$query_to_fetch = mysql_fetch_row($query_to_fetch) or die($this->sqlFatalError($query_to_fetch, $linenumber, $file));
return $query_to_fetch;
}
[...]
function sqlFatalError($sqlquery, $ln = 0, $f = "Not set")
{
$error = mysql_error();
$errno = mysql_errno();
$add_info .= "Line number where it went wrong: ".$ln."<br />\n";
$add_info .= "File in where it went wrong: ".$f."<br />\n";
if(!isset($add_info))
$add_info = "No Additional Information<br />\n";
echo "<font face=\"Verdana\" size=\"2\" color=\"#000000\"><strong>A serious error occured while trying to
use the MySQL driver.</strong><br />
Below you'll find more technical information about the error, this can be handy
when an administrator tries to solve the problem. So please contact an administrator to take a look at
this errormessage.</font><br /><br />
<table width=\"60%\" border=\"1\" bordercolor=\"#000000\" style=\"border-collapse: collapse\">
<tr>
<td><font face=\"Courier New\" size=\"2\"><b>MySQL error no.</b>: $errno<br />\n
<b>MySQL detailed errormessage</b>: $error<br />\n
<b>MySQL query that failed</b>: $sqlquery<br />\n
<b>Additional Information</b>:<br />\n $add_info</font></td>
</tr>
</table>";
}
?>

Does anyone have an idea? I posted this on many forums but without success. I was tipped by a friend to go to this site. He said there were some goog php'ers around here... Can you take a look at this one then, please?

[coopster]

mysql_fetch_row [php.net] returns

FALSE

if there are no more rows. Therefore, when your user-defined function

dbFetchQuery

is executed, and there are no more rows to process, your

[b]or[/b] condition

kicks in and ends after your user-defined function

sqlFatalError

because you specified it in a die [php.net] language construct.

Why the

[b]or[/b] condition

?

[Acolyte]

Why? Because when there is an error with the fetch the script calls in the fatalerror function which handles it.

[coopster]

Then you will have to change your error-handling logic for that function. Since mysql_fetch_row returns

FALSE

if there are no more rows the last fetch is always going to return

FALSE

and your error-handling logic is going to kick in. I would terminate the fetch statement and check for an error afterward and handle accordingly:

$query_to_fetch = mysql_fetch_row($query_to_fetch); 
if (mysql_errno()) die($this->sqlFatalError($query_to_fetch, $linenumber, $file)); 
return $query_to_fetch;  

mysql_errno [php.net] returns the error number from the last MySQL function, or 0 (zero) if no error occurred.

[Acolyte]

Thanks! That's realy the first good suggestion since I have this problem...!

But I thought of something that looks like that: just "kill" the error by putting a '@' in front of it. It's radical, I know. But your solution is a bit like this one: if the error no. is 0 then it's probably the extra loop that doesn't exist. So then you'll be doing the same but a little bit more elegant.

Am I right?

[coopster]

Not really. You would only be suppressing the error as opposed to handling it correctly. Does that make sense? It's like sweeping dirt under the rug, the job really isn't accomplished.

[Acolyte]

I guess you're right.
Thanks anyway! You really helped me out. I guess I can come back for some more support when I'm stuck again? :)

[coopster]

Absolutely. And by the way...Welcome to WebmasterWorld!