SQL query to generate Nested XML

Question

Hello,
I use Oracle 11g R2 SOE....
I have two main tables
COMMERCIALS_PROPERTIES (com_id number PK , com_size number, project_id number, com_type number)
COM_PHOTOS (ID number PK , com_id number FK, content blob, mimetype varchar2)
Please, note the following has nothing to do with my problem:
CONTENT and MIMETYPE columns. Also, the lookup tables: PROJECTS , COM_TYPE
In APEX ( Application Express ) we can expose a report as RESTful web service in XML format:
I am using this query to generate the XML 1 feed, but I need to tweak the query to generate XML 2 feed.
Is it possible, how to do it ???
Select
"COM"."COM_ID" as "COM_ID",
"COM"."COM_SIZE" as "SIZE",
"PROJECTS"."PROJECT_NAME_EN" as "PROJECT",
"COM_TYPES"."COM_TYPE" as "COM_TYPE",
'http://fam-erp.com/apex/erp/fateh/'||IMG.ID as "ImgURL"
FROM
COM_PHOTOS IMG inner join COMMERCIALS_PROPERTIES "COM"
on   IMG.COM_ID = COM.COM_ID
inner join "PROJECTS" "PROJECTS"
on "PROJECTS"."PROJECT_ID"="COM"."PROJECT_ID"
inner join "COM_TYPE_LOOKUP" "COM_TYPES"
on "COM_TYPES"."TYPE_ID"="COM"."COM_TYPE"
WHERE
  COM.COM_ID < 80 order by 1h1. XML 1
h2. Please look only at <COM_ID> and <ImgURL>
<ROWSET>
<ROW>
<COM_ID>77</COM_ID>
<SIZE>842</SIZE>
<PROJECT>Bayswater Tower</PROJECT>
<COM_TYPE>Office</COM_TYPE>
<ImgURL>http://fam-erp.com/apex/erp/fateh/1410</ImgURL>
</ROW>
<ROW>
<COM_ID>77</COM_ID>
<SIZE>842</SIZE>
<PROJECT>Bayswater Tower</PROJECT>
<COM_TYPE>Office</COM_TYPE>
<ImgURL>http://fam-erp.com/apex/erp/fateh/1412</ImgURL>
</ROW>
<ROW>
<COM_ID>78</COM_ID>
<SIZE>756</SIZE>
<PROJECT>Bayswater Tower</PROJECT>
<COM_TYPE>Office</COM_TYPE>
<ImgURL>http://fam-erp.com/apex/erp/fateh/1425</ImgURL>
</ROW>
<ROW>
<COM_ID>78</COM_ID>
<SIZE>756</SIZE>
<PROJECT>Bayswater Tower</PROJECT>
<COM_TYPE>Office</COM_TYPE>
<ImgURL>http://fam-erp.com/apex/erp/fateh/1429</ImgURL>
</ROW>
</ROWSET>---------------------------
h1. XML 2
h2. Please look only at <COM_ID> and <Images> and <ImgURL>
<ROWSET>
<ROW>
<COM_ID>77</COM_ID>
<SIZE>842</SIZE>
<PROJECT>Bayswater Tower</PROJECT>
<COM_TYPE>Office</COM_TYPE>
<Images>
      <ImgURL>http://fam-erp.com/apex/erp/fateh/1410</ImgURL>
      <ImgURL>http://fam-erp.com/apex/erp/fateh/1412</ImgURL>
</Images>
</ROW>
<ROW>
<COM_ID>78</COM_ID>
<SIZE>756</SIZE>
<PROJECT>Bayswater Tower</PROJECT>
<COM_TYPE>Office</COM_TYPE>
<Images>
        <ImgURL>http://fam-erp.com/apex/erp/fateh/1425</ImgURL>
        <ImgURL>http://fam-erp.com/apex/erp/fateh/1429</ImgURL>
</Images>
</ROW>
</ROWSET>

Answer 1

Hi, Fateh
One possible way is to use XML functions to create your XML.
Using XML functions you can do the IMAGES as an XMLAGG subquery rather than join to the image table.
Here's an example using SCOTT schema:
SQL> select xmlelement(
  2            "ROWSET"
  3          , xmlagg(
  4               xmlelement(
  5                  "ROW"
  6                , xmlforest(
  7                     d.deptno as "ID"
  8                   , d.dname as "NAME"
  9                   , (
10                        select xmlagg(
11                                  xmlelement(
12                                     "ImgUrl"
13                                   , 'http://the.server.com/'||e.empno
14                                  )
15                                  order by e.empno
16                               )
17                          from scott.emp e
18                         where e.deptno = d.deptno
19                     ) as "Images"
20                  )
21               )
22               order by d.deptno
23            )
24         ) the_xml
25    from scott.dept d
26    /* joins to the other tables EXCEPT image table */
27  /
THE_XML
<ROWSET><ROW><ID>10</ID><NAME>ACCOUNTING</NAME><Images><ImgUrl>http://the.serverThat output is an XMLTYPE column (think of it as a CLOB with added functionality ;-) )
My SQL*PLUS cuts the output, but believe me, it is all there.
Just to show it, here's the same example wrapped in an XMLSERIALIZE function to pretty-print the XML:
SQL> select xmlserialize(
  2            content
  3            xmlelement(
  4               "ROWSET"
  5             , xmlagg(
  6                  xmlelement(
  7                     "ROW"
  8                   , xmlforest(
  9                        d.deptno as "ID"
10                      , d.dname as "NAME"
11                      , (
12                           select xmlagg(
13                                     xmlelement(
14                                        "ImgUrl"
15                                      , 'http://the.server.com/'||e.empno
16                                     )
17                                     order by e.empno
18                                  )
19                             from scott.emp e
20                            where e.deptno = d.deptno
21                        ) as "Images"
22                     )
23                  )
24                  order by d.deptno
25               )
26            )
27            as varchar2(4000)
28            indent size=2
29         ) the_xml
30    from scott.dept d
31    /* joins to the other tables EXCEPT image table */
32  /
THE_XML
<ROWSET>
  <ROW>
    <ID>10</ID>
    <NAME>ACCOUNTING</NAME>
    <Images>
      <ImgUrl>http://the.server.com/7782</ImgUrl>
      <ImgUrl>http://the.server.com/7839</ImgUrl>
      <ImgUrl>http://the.server.com/7934</ImgUrl>
    </Images>
  </ROW>
  <ROW>
    <ID>20</ID>
    <NAME>RESEARCH</NAME>
    <Images>
      <ImgUrl>http://the.server.com/7369</ImgUrl>
      <ImgUrl>http://the.server.com/7566</ImgUrl>
      <ImgUrl>http://the.server.com/7788</ImgUrl>
      <ImgUrl>http://the.server.com/7876</ImgUrl>
      <ImgUrl>http://the.server.com/7902</ImgUrl>
    </Images>
  </ROW>
  <ROW>
    <ID>30</ID>
    <NAME>SALES</NAME>
    <Images>
      <ImgUrl>http://the.server.com/7499</ImgUrl>
      <ImgUrl>http://the.server.com/7521</ImgUrl>
      <ImgUrl>http://the.server.com/7654</ImgUrl>
      <ImgUrl>http://the.server.com/7698</ImgUrl>
      <ImgUrl>http://the.server.com/7844</ImgUrl>
      <ImgUrl>http://the.server.com/7900</ImgUrl>
    </Images>
  </ROW>
  <ROW>
    <ID>40</ID>
    <NAME>OPERATIONS</NAME>
  </ROW>
</ROWSET>For a webservice you do not need to pretty-print the XML that is returned by the webservice.
I do not know APEX, so I do not know if APEX supports exposing an allready built piece of XML rather than exposing a query result.
But my guess is that it should do it very nicely if you query an XMLTYPE datatype (that is - use the first of my examples rather than the pretty-printed one.)
If you can't get APEX to do it this way, then I suggest you try asking in the APEX forum rather than the SQL forum ;-)