[Help] Replace MySQL error message

Question

In insert form, I want to post a especial error message, instead of mysql_error
here an example:
if ((isset($_POST["MM_insert"])) && ($_POST["MM_insert"] == "insert_form")) {
  $insertSQL = sprintf("INSERT INTO stuff (title, numbers) VALUES (%s, %s)",
                       GetSQLValueString($_POST['titla'], "text"),
                       GetSQLValueString($_POST['numbers'], "int") );
  mysql_select_db($database_connection, $connection);
  $Result1 = mysql_query($insertSQL, $connection) or die(mysql_error());
cause i get an error like cannot be null
Thanks.
[Subject line edited by moderator to make it more meaningful]

Answer 1

If you want to replace the MySQL error message, you can put your own error message in quotes in the die() command. Change this:
$Result1 = mysql_query($insertSQL, $connection) or die(mysql_error());
to this:
$Result1 = mysql_query($insertSQL, $connection) or die('Database error');
However, that's not very helpful to a user, because all that will be displayed is "Database error" with no indication of what caused the error or any way of returning to the page, except by using the browser back button.
A better way of handling things is to remove the or die(mysql_error()) section of code altogether and replace it with a PHP conditional statement that sends the user to an error page if the SQL fails for any reason. However, making these changes will prevent you from making further edits to the server behavior through the Server Behaviors panel.
$Result1 = mysql_query($insertSQL, $connection);
if (!$Result1) {
  $insertGoTo = 'error.php';
} else {
  $insertGoTo = 'another_page.php' // <-- this is the original $insertGoTo line