Challenge: Grab N rows AFTER performing sort

Question

I am not an SOA developer, but am working with a team of people who use the tool to develop software for us. I have stated a business requirement which the developers tell me SOA cannot do. I am certain they are wrong, but not being versed in SOA, I'm unable to debate the point without turning to experts for help.
All I want to do is select N+ rows from my table after it has been sorted on the "importance" column, i.e., "Give me the top 100 rows ordered by importance". I am also filtering on a "status" column, taking only those rows that have statue='A'.
To code this in raw SQL, I would simply say:
SELECT *
FROM (
SELECT <my fields>
FROM <my table>
WHERE
STATUS = 'A'
ORDER BY importance ASC
) where rownum <=100
The way they have solved this issue in SOA is generating the following (again in native SQL):
SELECT <my fields>
FROM <my table>
WHERE
STATUS = 'A'
AND ROWNUM <=100
ORDER BY importance ASC
These two are not equivalent, and the second query does not satisfy the goal. The developers are telling me that it is impossible to satisfy my query using SOA.
The actual SQL that got generated by SOA is:
     SELECT <my fields>
FROM <my table>
WHERE
STATUS = :1
AND ROWNUM <= :2
ORDER BY importance ASC
FOR UPDATE NOWAIT
Is there some way to get SOA to generate THIS instead? :
SELECT <my fields>
FROM (
     SELECT <my fields>
FROM <my table>
WHERE
STATUS = :1
ORDER BY importance ASC
WHERE ROWNUM <= :2
FOR UPDATE NOWAIT
Edited by: user10593614 on Apr 26, 2012 6:49 AM

Answer 1

The DB Adapter is able to call PLSQL API's.
I have copied and pasted some code we used from one of recent patches:
- Create a type var for the results of your query
CREATE OR REPLACE TYPE ICSOA_ARAUTOINV_DISTRIB_TYP AS OBJECT(
FIELD1 VARCHAR2(30),
FIELD2 VARCHAR2(30)
- Create a table of this type
CREATE OR REPLACE TYPE ICSOA_ARAUTOINV_DISTRIB_TBL AS TABLE OF ICSOA_ARAUTOINV_DISTRIB_TYP;
- Create your PLSQL using the params you need as simple types something like: (In a package)
function CreateAction(
     p_param1 in number,
     p_parm2 in VARCHAR2,
     p_result out ICSOA_ARAUTOINV_DISTRIB_TBL,
     p_err_message out varchar2
) return number;
- your fuction devlaration section needs a cursor something like
cursor c_lines_rsp(p_1 in number, p_2 in varchar2) is
select ICSOA_ARAUTOINV_DISTRIB_TYP(123,'rrr') from dual
where p_1=1 and p_2='abc';
- in your plsql have it return 0 on success and in the exception handler get it to put the error message in p_err_message:
begin
--use cursor to get data
OPEN c_lines_rsp(p_param1,p_param2);
FETCH c_lines_rsp BULK COLLECT INTO p_result;
CLOSE c_lines_rsp;
return 0;
EXCEPTION
WHEN OTHERS THEN
x_err_message := 'Unknown Error ' || sqlerrm || ' ' || DBMS_UTILITY.FORMAT_ERROR_BACKTRACE;
return 99;
end;
If you point the DB adapater at this it will create all the nessecary xml's and wsdls. It should be easy to call this from a BPEL process.
The DB Adapter will create the object var and table but prefer creating my own as it fits in better with the patching process.
From experence I have learned to always return the error message to BPEL it makes debugging a lot easier.
oh and you shouldn't use and commit or rollback statements in your PLSQL if you are using XA db connections. (SOA will preform a commit for you)
Robert
Edited by: RobertMetcalf on Apr 26, 2012 4:09 PM