Right, I've had a good mess with this now and here's my code:

use strict;
use diagnostics;
#use warnings;

use CGI qw(:standard);
use CGI::Carp qw/fatalsToBrowser/;

use Win32::ODBC;
use lib '/perlcgi/settings';
require 'settings.pl';  # Included configuration file which contains g
+lobal variables

my %labels = (
    MA    => 'Mortgage Advisers',
    CA    => 'Customer Advisers',
    BM    => 'Branch Management',
    HO    => 'Head Office',
    Acc    => 'Accord',
    MSa    => 'MCC Sales',
    MSe    => 'MCC Service',
);

my $cgi    = CGI->new;
my $dept    = $cgi->param('department');
print $cgi->header('text/html');

if (defined $dept) {
    if (exists $labels{$dept}) {
        # FIXME
        # untaint $dept and put it into database
        print
            $cgi->start_html,
            $cgi->p("$dept was received.");
            if ($dept =="CA") {
            my $db = new Win32::ODBC('$DSN');
if (!($db=new Win32::ODBC('$DSN'))) {
  $cgi->p("Error connecting to Database");
  $cgi->p("Error: " . Win32::ODBC::Error() . " ");
}
my $SqlStatement ='SELECT * FROM Pipeline WHERE Publish<="19 Apr 2006"
+ AND Expiry>="19 Apr 2006" AND CA="Must Read"';
print $SqlStatement;
    $db->Sql('$SqlStatement');
             }
            $cgi->end_html;
  } else {
        print
            $cgi->start_html,
            $cgi->p("$dept was received, but is not a valid department
+ name."),
            $cgi->end_html;
    };
} else {
    print
        $cgi->start_html,
        $cgi->start_form(
            -action    => $cgi->script_name,
        ),
        $cgi->popup_menu(
            -name        => 'department',
            -values        => [keys %labels],
            -labels        => \%labels,
        ),
        $cgi->submit,
        $cgi->end_form,
        $cgi->end_html;
};

This is what prints out:
<code>
CA was received.

SELECT * FROM Pipeline WHERE Publish<="19 Apr 2006" AND Expiry>="19 Ap
+r 2006" AND CA="Must Read"

Software error:
Can't call method "Sql" on an undefined value at E:\Perlcgi\Pipeline\c
+gi.pl line 50.
[download]

Now I really don't get it.

Interestingly it seems to do the database connection no matter what the value of $dept.