if /^(([A-Za-z][A-Za-z0-9]*)(\.([A-Za-z][A-Za-z0-9]*))*)(\s|,|=)/
{
  (/\(CONNECT_DATA\s+=\s+\(SID\s+=\s+(\w+\d+?)(\s+)?\)/)
    {  
      $hashref->{$1}="";
    }
}

##</code><code>##

DB1.UK, DB2.UK =
  (
    (ADDRESS = (PROTOCAL = TCP))
    (CONNECT_DATA = (SID = db1))
  )

DB1.EU, DB2.CH =
  (
    (ADDRESS = (PROTOCAL = TCP))
    (CONNECT_DATA = (SID = db1))
  )

DB3.UK =
  (
    (ADDRESS = (PROTOCAL = TCP))
    (CONNECT_DATA = (SID = db3))
  )

DB3.US =
  (
    (ADDRESS = (PROTOCAL = TCP))
    (CONNECT_DATA = (SID = db3))
  )

DB5.UK.US, DB5.US =
  (
    (ADDRESS = (PROTOCAL = TCP))
    (CONNECT_DATA = (SID = db5))
  )


##</code><code>##

DB1.UK
DB3.UK
DB5.UK.US