use strict;
use warnings;
use Getopt::Long;
use DBI;

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 => 'host1', db=>'db1', user=>'user1', pw=>'pw1' },
	site2 => { host => 'host2', db=>'db2', user=>'user2', pw=>'pw2' },
	site3 => { host => 'host3', db=>'db3', user=>'user3', pw=>'pw3' },
);

my $dbh = dbconnect($site);

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}{user}, $site_map{$s}{pw})
		or die "ERROR: can't connect to database server site $s";
	return $dbh;
}