if($name =~ /^[a-z0-9_]$/i && $name !~ /^(?:master|model|dbccdb|sybsecurity|sybsystemdb|sybsystemprocs|tempdb|DBA)$/)
{
  print "allowed\n"
}
else
{
  print "not allowed\n"
}

##</code><code>##

if($name =~ /^(?!(master|model|dbccdb|sybsecurity|sybsystemdb|sybsystemprocs|tempdb|DBA)$)(^[a-z0-9_]+$)/i)
{
  print "allowed\n"
}
else
{
  print "not allowed\n"
}