protected boolean isValidIdentifier(String identifier){
  if (identifier.isEmpty())   return false;
  for (int i=0; i < identifier.length(); i++) {
    if (!Character.isDigit(identifier.charAt(i)))     return false;
  }
  return true;
}

protected boolean isValidIdentifier ( String identifier ) { if ( identifier . isEmpty ( ) ) return false ; for ( int i = 0 ; i < identifier . length ( ) ; i ++ ) { if ( ! Character . isDigit ( identifier . charAt ( i ) ) ) return false ; } return true ; }
returns whether the given string is a valid identifier within the jdbc authentication extension . invalid identifiers may result in sql errors from the underlying database when used in queries .
