Custom Error Page and string help

[treeleaf20]

If I have a SQL error and I die(mysql_error) instead of doing that is it to just redirect a user to a custom error page. Would something like die("http://www.website.com/error.php") work?

Also I have a qustion regarding string manipulation. If I have a form where a user can enter something with a space or a period like St. Louis or Washington D.C. as an example. When that posts to the next page I would like convert that sting to something like st_louis and washington_dc. So maybe make spaces into underscores and just ignore periods. Is this possible and if it is could someone show me how? Thanks

[gammaster]

Question 1:

if(mysql_error() != '') {
   header("Location: errorDoc.php");
   exit;
   }

Question 2:

$inputString = $_POST['fieldName'];

$inputString = str_replace('.', '_', $inputString); // replace periods
$inputString = str_replace(' ', '_', $inputString); // replace space
$inputString = str_replace('__', '_', $inputString); // replace possible double underscores