catch mysql error and log it in php

i have the following code...

(functions.php)

$result = mysql_query($sql) or die(mysql_error($result)." query: ".$sql);

(init.php)

set_error_handler("custom_error_handler");

// custom error handler to report our problems
function custom_error_handler($error_level,$error_message,$error_file,$error_line,$error_context) {
  switch ($error_level){
  case 2:        
    $error_report="E_WARNING : Non-fatal run-time errors. Execution of the script is not halted";
    break;
  case 8:       
    $error_report="E_NOTICE : Run-time notices. The script found something that might be an error, but could also happen when running a script normally";
    break;
  case 256:       
    $error_report="E_USER_ERROR : Fatal user-generated error. This is like an E_ERROR set by the programmer using the PHP function trigger_error()";
    break;  
  case 512:       
    $error_report="E_USER_WARNING : Non-fatal user-generated warning. This is like an E_WARNING set by the programmer using the PHP function trigger_error()";
    break;
  case 1024:       
    $error_report="E_USER_NOTICE : User-generated notice. This is like an E_NOTICE set by the programmer using the PHP function trigger_error()";
    break;
  case 4096:       
    $error_report="E_RECOVERABLE_ERROR : Catchable fatal error. This is like an E_ERROR but can be caught by a user defined handle (see also set_error_handler())";
    break;
  case 8191:       
    $error_report="E_ALL : All errors and warnings, except level E_STRICT (E_STRICT will be part of E_ALL as of PHP 6.0)";
    break;
  }  
  $temp_user=$_SESSION['user_username'];
  $temp_ip=$_SERVER['REMOTE_ADDR'];
  $error_display="
  <b>Error Type:</b> [$error_level] $error_report.<br />
  <b>Error Message:</b> $error_message<br />
  <b>Filename: $error_file</b> <br />
  Line #:$error_line<br />
  Context: $error_context<br />
  User: $temp_user<br />
  IP: $temp_ip<br />
  ";
 
  db_connect();
  // get current time minus time limit to see if its ok to send another email error
  $temp_time=time();
  $sql="INSERT INTO error_time SET error_timestamp=$temp_time, error_text='".db_string_mysqlsafe($error_display)."'";
  $insert = mysql_query($sql);
 
  // prevent email flooding, check for errors in past hour or so otherwise send an email
    $sql="SELECT count(*) as c FROM error_time WHERE (UNIX_TIMESTAMP(now()) - 3600 ) <= error_timestamp";
      $result = mysql_query($sql);
      if ($row=mysql_fetch_array($result)){
        $count=$row['c'];
      }
      if($count==0 || $count=='0'){
      //print $error_display;
      error_log("Site errored, check error logs",1, "me@me.com","From: webmaster@me.com\nsubject  :Site ERROR\nContent-Type: text/html; charset=ISO-8859-1");
      }
   
}



The problem is when the $result fails it doesnt log the actual mysql query it just tells me i have an error on that line. When a sql query errors how can I log the actual query so i can fix it??Start Free Trial