mysql_error

Florian Sidler (2010-02-02 02:33:07)

Be aware that if you are using multiple MySQL connections you MUST support the link identifier to the mysql_error() function. Otherwise your error message will be blank.
Just spent a good 30 minutes trying to figure out why i didn't see my SQL errors.

Pendragon Castle (2009-01-13 07:16:19)

Using a manipulation of josh ><>'s function, I created the following. It's purpose is to use the DB to store errors. It handles both original query, as well as the error log. Included Larry Ullman's escape_data() as well since I use it in q().

<?php
function escape_data($data){
 global $dbc;
 if(ini_get('magic_quotes_gpc')){
  $data=stripslashes($data);
 }
 return mysql_real_escape_string(trim($data),$dbc);
}

function q($page,$query){ 
// $page
 $result = mysql_query($query);
 if (mysql_errno()) {
  $error = "MySQL error ".mysql_errno().": ".mysql_error()."\n<br>When executing:<br>\n$query\n<br>";
  $log = mysql_query("INSERT INTO db_errors (error_page,error_text) VALUES ('$page','".escape_data($error)."')");
 }
}

// Run the query using q()
$query = "INSERT INTO names (first, last) VALUES ('myfirst', 'mylast'");
$result = q("Sample Page Title",$query);
?>

Gianluigi_Zanettini-MegaLab.it (2007-05-25 03:50:00)

A friend of mine proposed a great solution.

<?php
$old_track = ini_set('track_errors', '1');

.....

        if ($this->db_handle!=FALSE && $db_selection_status!=FALSE)
            {
            $this->connected=1;
            ini_set('track_errors', $old_track);
            }
        else
            {
            $this->connected=-1;
            $mysql_warning=$php_errormsg;
            ini_set('track_errors', $old_track);
            throw new mysql_cns_exception(1, $mysql_warning . " " . mysql_error());
            }
?>

Gianluigi_Zanettini-MegaLab.it (2007-05-25 01:20:10)

"Errors coming back from the MySQL database backend no longer issue warnings." Please note, you have an error/bug here. In fact, MySQL 5.1 with PHP 5.2:
Warning: mysql_connect() [function.mysql-connect]: Unknown MySQL server host 'locallllllhost' (11001)
That's a warning, which is not trapped by mysql_error()!

phpnet at robzazueta dot com (2007-01-23 23:14:09)

This is a big one - As of MySQL 4.1 and above, apparently, the way passwords are hashed has changed. PHP 4.x is not compatible with this change, though PHP 5.0 is. I'm still using the 4.x series for various compatibility reasons, so when I set up MySQL 5.0.x on IIS 6.0 running PHP 4.4.4 I was surpised to get this error from mysql_error():
MYSQL: Client does not support authentication protocol requested by server; consider upgrading MySQL client
According to the MySQL site (http://dev.mysql.com/doc/refman/5.0/en/old-client.html) the best fix for this is to use the OLD_PASSWORD() function for your mysql DB user. You can reset it by issuing to MySQL:
Set PASSWORD for 'user'@'host' = OLD_PASSWORD('password');
This saved my hide.

l dot poot at twing dot nl (2006-07-12 05:38:21)

When creating large applications it's quite handy to create a custom function for handling queries. Just include this function in every script. And use db_query(in this example) instead of mysql_query.

This example prompts an error in debugmode (variable $b_debugmode ). An e-mail with the error will be sent to the site operator otherwise.

The script writes a log file in directory ( in this case /log ) as well.

The system is vulnerable when database/query information is prompted to visitors. So be sure to hide this information for visitors anytime.

Regars,

Lennart Poot
http://www.twing.nl

<?php
$b_debugmode = 1; // 0 || 1

$system_operator_mail = 'developer@company.com';
$system_from_mail = 'info@mywebsite.com';

function db_query( $query ){
  global $b_debugmode;
  
  // Perform Query
  $result = mysql_query($query);

  // Check result
  // This shows the actual query sent to MySQL, and the error. Useful for debugging.
  if (!$result) {
    if($b_debugmode){
      $message  = '<b>Invalid query:</b><br>' . mysql_error() . '<br><br>';
      $message .= '<b>Whole query:</b><br>' . $query . '<br><br>';
      die($message);
    }

    raise_error('db_query_error: ' . $message);
  }
  return $result;
}

  function raise_error( $message ){
    global $system_operator_mail, $system_from_mail;

    $serror=
    "Env:       " . $_SERVER['SERVER_NAME'] . "\r\n" .
    "timestamp: " . Date('m/d/Y H:i:s') . "\r\n" .
    "script:    " . $_SERVER['PHP_SELF'] . "\r\n" .
    "error:     " . $message ."\r\n\r\n";

    // open a log file and write error
    $fhandle = fopen( '/logs/errors'.date('Ymd').'.txt', 'a' );
    if($fhandle){
      fwrite( $fhandle, $serror );
      fclose(( $fhandle ));
     }
  
    // e-mail error to system operator
    if(!$b_debugmode)
      mail($system_operator_mail, 'error: '.$message, $serror, 'From: ' . $system_from_mail );
  }

?>

(2005-01-05 00:53:45)

My suggested implementation of mysql_error():
$result = mysql_query($query) or die("<b>A fatal MySQL error occured</b>.\n<br />Query: " . $query . "<br />\nError: (" . mysql_errno() . ") " . mysql_error());
This will print out something like...
A fatal MySQL error occured.
Query: SELECT * FROM table
Error: (err_no) Bla bla bla, you did everything wrong
It's very useful to see your query in order to detect problems with syntax. Most often, the output message from MySQL doesn't let you see enough of the query in the error message to let you see where your query went bad- it a missing quote, comma, or ( or ) could have occured well before the error was detected. I do -not- recomend using this procedure, however, for queries which execute on your site that are not user-specific as it has the potential to leak sensative data. Recomended use is just for debugging/building a script, and for general user-specific queries which would at the worst, leak the users own information to themself.
Good luck,
-Scott

aleczapka _at) gmx dot net (2004-07-16 10:05:29)

If you want to display errors like "Access denied...", when mysql_error() returns "" and mysql_errno() returns 0, use $php_errormsg. This Warning will be stored there. You need to have track_errors set to true in your php.ini.
Note. There is a bug in either documentation about error_reporting() or in mysql_error() function cause manual for mysql_error(), says: "Errors coming back from the MySQL database backend no longer issue warnings." Which is not true.

olaf at amen-online dot de (2004-06-22 11:08:27)

When dealing with user input, make sure that you use
<?php
echo htmlspecialchars (mysql_error ());
?>
instead of
<?php
echo mysql_error ();
?>

Otherwise it might be possible to crack into your system by submitting data that causes the SQL query to fail and that also contains javascript commands.

Would it make sense to change the examples in the documentation for mysql_query () and for mysql_error () accordingly?

miko_il AT yahoo DOT com (2003-12-11 11:25:30)

Following are error codes that may appear when you call MySQL from any host language:
http://www.mysql.com/doc/en/Error-returns.html

josh ><> (2003-10-13 16:26:01)

Oops, the code in my previous post only works for queries that don't return data (INSERT, UPDATE, DELETE, etc.), this updated function should work for all types of queries (using $result = myquery($query);):
function myquery ($query) {
$result = mysql_query($query);
if (mysql_errno())
echo "MySQL error ".mysql_errno().": ".mysql_error()."\n<br>When executing:<br>\n$query\n<br>";
return $result;
}

scott at rocketpack dot net (2003-07-25 02:44:12)

My suggested implementation of mysql_error():
$result = mysql_query($query) or die("<b>A fatal MySQL error occured</b>.\n<br />Query: " . $query . "<br />\nError: (" . mysql_errno() . ") " . mysql_error());
This will print out something like...
<b>A fatal MySQL error occured</b>.
Query: SELECT * FROM table
Error: (err_no) Bla bla bla, you did everything wrong
It's very useful to see your query in order to detect problems with syntax. Most often, the output message from MySQL doesn't let you see enough of the query in the error message to let you see where your query went bad- it a missing quote, comma, or ( or ) could have occured well before the error was detected. I do -not- recomend using this procedure, however, for queries which execute on your site that are not user-specific as it has the potential to leak sensative data. Recomended use is just for debugging/building a script, and for general user-specific queries which would at the worst, leak the users own information to themself.
Good luck,
-Scott

(2001-05-10 07:03:38)

some error can't handle. Example:
ERROR 1044: Access denied for user: 'ituser@mail.ramon.intranet' to database 'itcom'
This error ocurrs when a intent of a sql insert of no authorized user. The results: mysql_errno = 0 and the mysql_error = "" .