This sounds. . . interesting ;)

Is this a CGI app or a client/server app? If CGI, I take it this app is installed multiple times in multiple places? I'm just wondering why you need to have the different code. By using DBI, you can make it easy to switch between various databases and not have to change any code. Behold my untested (simple) example:

if($dbms eq "mysql")
{
    $driver = "mysql";
    $db     = "test";
    $user   = "root";
    $pw     = "";
}
elsif($dbms eq "mssql"
{
    $driver = "ODBC";
    $db     = "test";
    $user   = "sa";
    $pw     = "";
}

my $dbh = DBI->connect("DBI:$driver:$db", $user, $pw, 
  { RaiseError => 1});
[download]

If you don't want to use ODBC, you might consider using DBD::Sybase. Haven't tried it, but SQL Server is derived from Sybase, so you might have some luck there.

Is this what you're looking for, or am I completely misunderstanding?

MrCromeDome