Need to return data from a query in different ways - Please help

Question

We are using 10g R2
I have a proc as follows that has a query with over 100 values in the select clause:
proc one( input param1, input_param2,.... output_cursor )
as
begin
open cursor for
select ...about 100 values with most of them being calculated
from table1, view 1, table2, table 3, view 2 ...
where ....
and table1.col1 = input param1
and table1.col2 = input param 2
and view1.col5 = input param5...
end;
I need to return the data that comes from the above query in different formats, columns for a report would be different from columns for screen A and different for screen B. I need only certain columns for a report and different set of columns for another screen. I have wrapper procs that get different input params. From the wrapper procs I intend to call the above proc but would like only selected values.
How can I accomplish this? Since my main goal is to select different columns for each wrapper I was thinking of insert the data from the above proc into global temp table and selecting whatever columns and order I want from the wrappers.
What do you think? Any other solutions?
Thanks
Edited by: user565033 on Jan 21, 2013 7:50 PM

Answer 1

You need to clearly separate roles and responsibilities. The PL/SQL code that creates and supplies a cursor handle is server code tasked to supply data. The code that makes the call for server data, is responsible for formatting and rendering that data.
Thus moving data formatting into the server code needs to be question. Simple example. Cursor does not return invoice date as a date - but formats it into a string using TO_CHAR().
This works for client1 - as that is the date format expected. However, client2 has different International settings and specifies a different date format. Invoice date, formatted into a string by the server, now renders in the wrong format on client2.
Server code should not be concerned with rendering and formatting of data send to a client.
As for the idea to use a global temp table is ..., well to put it nicely, it smells. Badly.
The single most expensive operation on a database platform is I/O. And now you want to read server data and write it to temporary storage, and the read data from temporary storage to return to the client? What on earth for!? Why purposefully increase the size of the I/O workload? Why decrease performance and undermine scalability?
Provide a proper abstraction interface to the client. Enable it to specify (as simplistically as possible) what it wants ito data. There are a number of ways to design and implement this in PL/SQL. Simplistic example:
SQL> create or replace package Employees as
  2 
  3          EMP_FULL_DETAILS        constant integer := 1;
  4          EMP_BASIC_DETAILS       constant integer := 2;
  5 
  6          procedure GetEmpByID(
  7                  cur out sys_refcursor,
  8                  empID in emp.empno%type,
  9                  template in integer default EMP_BASIC_DETAILS
10          );
11 
12          procedure GetEmpByName(
13                  cur out sys_refcursor,
14                  empName in emp.ename%type,
15                  template in integer default EMP_BASIC_DETAILS
16          );
17  end;
18  /
Package created.
SQL>
SQL> create or replace package body Employees as
  2 
  3  type TArray is table of varchar2(32767);
  4 
  5  TemplateList       constant TArray :=
  6          new TArray(
  7                  'EMPNO, ENAME, JOB, MGR, HIREDATE, SAL, COMM, DEPTNO ',
  8                  'EMPNO, ENAME, JOB '
  9          );
10 
11  procedure GetEmpByID(
12          cur out sys_refcursor,
13          empID in emp.empno%type,
14          template in integer default EMP_BASIC_DETAILS
15  ) is
16          sqlSelect       varchar2(32767);
17  begin
18          sqlSelect :=
19                  'select '||TemplateList(template)||
20                  'from emp where empno = :empID';
21 
22          open cur for sqlSelect using empID;
23  end;
24 
25  procedure GetEmpByName(
26          cur out sys_refcursor,
27          empName in emp.ename%type,
28          template in integer default EMP_BASIC_DETAILS
29  ) is
30          sqlSelect       varchar2(32767);
31  begin
32          sqlSelect :=
33                  'select '||TemplateList(template)||
34                  'from emp where ename like :empName';
35          open cur for sqlSelect using empName;
36  end;
37 
38 
39  end;
40  /
Package body created.
SQL>
SQL> var c refcursor
SQL>
SQL> exec Employees.GetEmpByID( :c, 7499 );
PL/SQL procedure successfully completed.
SQL> print c
     EMPNO ENAME      JOB
      7499 ALLEN      SALESMAN
SQL>
SQL> exec Employees.GetEmpByName( :c, 'A%', Employees.EMP_FULL_DETAILS );
PL/SQL procedure successfully completed.
SQL> print c
     EMPNO ENAME      JOB               MGR HIREDATE                   SAL       COMM     DEPTNO
      7499 ALLEN      SALESMAN         7698 1981/02/20 00:00:00       1600        300         30
      7876 ADAMS      CLERK            7788 1987/05/23 00:00:00       1100                    20
SQL>