$database="testdb";
$suid=1234;
$loginname="joe";

$sth=$dbh->prepare("declare \@name  char(30) declare \@uid   int select \@name=name, \@uid=uid from $database..sysusers where suid
= $suid if (\@name != null)  exec $database..sp_dropuser \@name  else if exists (select 1 from $database..sysal
ternates where suid = $suid) exec $database..sp_dropalias $loginname");
$sth->execute;