private String translateBinary2(String op, RexNode left, RexNode right) {

      switch (right.getKind()) {

      case LITERAL:

        break;

      default:

        return null;

      }

      final RexLiteral rightLiteral = (RexLiteral) right;

      switch (left.getKind()) {

      case INPUT_REF:

        final RexInputRef left1 = (RexInputRef) left;

        String name = fieldNames.get(left1.getIndex());

        return translateOp2(op, name, rightLiteral);

      case CAST:

        return translateBinary2(op, ((RexCall) left).operands.get(0), right);

      default:

        return null;

      }

    }