code: private boolean isTransactional(SqlAction[] sqlActions, XianTransaction transaction) {
          int count = 0;
          for (SqlAction sqlAction : sqlActions) {
              if (!(sqlAction instanceof ISelect)) {
                  count++;
              }
          }
          return count > 1 || transaction.isBegun();
      }
docs: judge whether we need to begin the transaction.
  If there are more than one non-query sql actions in this dao unit, a new transaction will be begun.
  if a transaction is already begun, a nested transaction will be begun.
  Else no transaction will be begun.
  
  @return true if this unit is transacitonal false otherwise.