XML parent child records

Question

Hello
I am trying to mimic the FOR XML EXPLICIT behavior of SQL Server code in Oracle 11g.
The XML EXPILICT mode transforms the rowset that results from the query execution into an XML document and it preserves the parent child relationship in the XML output. For example
SELECT customer.id,customer.name,order.id,order.date,orderdetail.id,orderdetail.pid
FROM CUSTOMER,ORDER,ORDERDETAIL
WHERE CUSTOMER.ORDERID=ORDER.ORDERID
AND
ORDER.ORDERID=ORDERDETAIL.ORDERID
<Customer ID="C1" name="Ann">
<Order id="O1" date="1/20/2008">
<OrderDetail id="OD1" pid="P1"/>
<OrderDetail id="OD2" pid="P2"/>
</Order>
<Order id="O2" date="3/29/1997">
</Customer>
<Customer ID="C2" name="Jack">
<Order id="O1" date="1/20/2009">
<OrderDetail id="OF1" pid="P1"/>
<OrderDetail id="OF2" pid="P2"/>
</Order>
<Order id="O2" date="3/29/1997">
<OrderDetail id="OX1" pid="D1"/>
<OrderDetail id="OX2" pid="D2"/>
</Order>
</Customer>
Appreciate if you can help me to write an Oracle equivalent of this code.
Thanks & Regards

Answer 1

You can use xmlelement and xmlagg functions this way:
SQL> with customer as (
  2  select 'C1' id, 'Ann' name from dual union
  3  select 'C2' id, 'Jack' name from dual),
  4  Orders as (
  5  Select 'O1' id, '1/20/2008' odate, 'C1' custid from dual union
  6  Select 'O2' id, '3/29/1997' odate, 'C1' custid from dual union
  7  Select 'O3' id, '1/20/2008' odate, 'C2' custid from dual union
  8  Select 'O4' id, '3/29/1997' odate, 'C2' custid from dual),
  9  orderdetail as (
10  select 'OD1' id, 'P1' pid, 'O1' orderid from dual union
11  select 'OD2' id, 'P2' pid, 'O1' orderid from dual union
12  select 'OF1' id, 'P1' pid, 'O3' orderid from dual union
13  select 'OF2' id, 'P2' pid, 'O3' orderid from dual union
14  select 'OX1' id, 'D1' pid, 'O4' orderid from dual union
15  select 'OX2' id, 'D2' pid, 'O4' orderid from dual
16  )
17  -- End of test data, actual query follows
18  SELECT xmlagg(
19           xmlelement("Customer",
20                      xmlattributes(id, name),
21                      (select xmlagg(
22                                xmlelement("Order",
23                                           xmlattributes(o.id, o.odate as "date"),
24                                           (select xmlagg(
25                                                     xmlelement("OrderDetail",
26                                                                xmlattributes(id,pid),
27                                                                null
28                                                                )
29                                                          )
30                                              from orderdetail d
31                                             where d.orderid = o.id
32                                            )
33                                           )
34                                     )
35                         from orders o
36                        where CUSTOMER.ID=O.CUSTID
37                       )
38                      )
39                 ).extract('/*') xml
40    from customer;
XML
<Customer ID="C1" NAME="Ann">
  <Order ID="O1" date="1/20/2008">
    <OrderDetail ID="OD1" PID="P1"/>
    <OrderDetail ID="OD2" PID="P2"/>
  </Order>
  <Order ID="O2" date="3/29/1997"/>
</Customer>
<Customer ID="C2" NAME="Jack">
  <Order ID="O3" date="1/20/2008">
    <OrderDetail ID="OF1" PID="P1"/>
    <OrderDetail ID="OF2" PID="P2"/>
  </Order>
  <Order ID="O4" date="3/29/1997">
    <OrderDetail ID="OX1" PID="D1"/>
    <OrderDetail ID="OX2" PID="D2"/>
  </Order>
</Customer>Max
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