How to use

withOrder

method

in

org.apache.calcite.rel.rel2sql.SqlImplementor$Context

/** Converts a call to an aggregate function to an expression. */
public SqlNode toSql(AggregateCall aggCall) {
 final SqlOperator op = aggCall.getAggregation();
 final List<SqlNode> operandList = Expressions.list();
 for (int arg : aggCall.getArgList()) {
  operandList.add(field(arg));
 }
 final SqlLiteral qualifier =
   aggCall.isDistinct() ? SqlSelectKeyword.DISTINCT.symbol(POS) : null;
 final SqlNode[] operands = operandList.toArray(new SqlNode[0]);
 List<SqlNode> orderByList = Expressions.list();
 for (RelFieldCollation field : aggCall.collation.getFieldCollations()) {
  addOrderItem(orderByList, field);
 }
 SqlNodeList orderList = new SqlNodeList(orderByList, POS);
 if (op instanceof SqlSumEmptyIsZeroAggFunction) {
  final SqlNode node =
    withOrder(
      SqlStdOperatorTable.SUM.createCall(qualifier, POS, operands),
      orderList);
  return SqlStdOperatorTable.COALESCE.createCall(POS, node,
    SqlLiteral.createExactNumeric("0", POS));
 } else {
  return withOrder(op.createCall(qualifier, POS, operands), orderList);
 }
}