}
# Display error if username or password fields are left blank 
if($user_name eq "" || $password eq "") {

         &error();

} else {

#check if the user name and password are in the database
$sth = $db->prepare(q{SELECT user_id, password from user where user_id = ?})
$sth->execute($user_name)
                
while(@row  = $sth->fetchrow_array){

         if($user_name eq $row[0] && $password eq $row[1])
         {
                   #go to main page
         } else {
# If the username or password are not in the database                                                                       if($user_name ne $row[0] || $password ne $row[1])                                        {

                  &error();
}