use Getopt::Long;
GetOptions("site=s" => \my $site)
    or die "Error in command line arguments\n";
    
defined $site
    or die "usage: $0 site_name\n";

my %site_map = (
   site1 => { host => 'am.d.aog.com', db=>'site1', user=>'db_cad', pw=>'Cad123' },
    site2 => { host => 'am.d.aog.com', db=>'site2', user=>'db_cad', pw=>'Cad123' },
);

my $dbh = dbconnect($site);
print $dbh;

sub dbconnect {
    my $s = shift;
    die "bad site $s" unless $site_map{$s};
    my $dsn = "DBI:mysql:database=$site_map{$s}{db};host=$site_map{$s}{host}";
    my $dbh = DBI->connect($dsn, $site_map{$s}{'current'}{user}, $site_map{$s}{'current'}{pw})
        or die "ERROR: can't connect to database server site $s";
    return $dbh;
}