Multiple values in 1 application context

Question

All, I'm trying to return multiple values from a query and store them in an application context.
I have an employee that can be a part of multiple divisions. I already captured emp_id:
dbms_session.set_context('COMPANY', 'emp_id', emp_id);
but also want to capture division_id for the person. Most people will only have 1 division_id, but some will have multiple division_id's.
What's the best way for me to capture multiple numeric values and store them in an application context like this.
I'm trying to set up VPD policies and don't have to have to reissue a query every time I need to access the division_id.
Thanks,
Jon.

Answer 1

One option would be to store a comma-delimited list of the division_ids in the context and then your VPD filter can use this and the TABLE function to limit the rows:
sql>create or replace type NumberTable as table of number;
  2  /
Type created.
sql>create or replace function f_number_table(
  2    p_list       in  varchar2,
  3    p_delimiter  in  varchar2 default ',')
  4    return numbertable
  5  is
  6    v_string  long := p_list || p_delimiter;
  7    v_pos     pls_integer;
  8    v_data    numbertable := numbertable();
  9  begin
10    loop
11      v_pos := instr(v_string, p_delimiter);
12      exit when (nvl(v_pos, 0) = 0);
13      v_data.extend;
14      v_data(v_data.count) := trim(substr(v_string, 1, v_pos - 1));
15      v_string := substr(v_string, v_pos + 1);
16    end loop;
17    return (v_data);
18  end f_number_table;
19  /
Function created.
Then, in your VPD package:
-- build a list of the division_ids by looping through a cursor
-- set the context using this list of division_ids:
dbms_session.set_context('company', 'div_id', '10,20');
-- later, you would replace the literal value below with a call to sys_context to retrieve it
sql>select empno, ename, deptno
  2    from emp
  3   where deptno in (select *
  4                      from table(f_number_table('10,20')));
    EMPNO ENAME         DEPTNO
     7782 CLARK             10
     7839 KING              10
     7934 MILLER            10
     7369 SMITH             20
     7876 ADAMS             20
     7902 FORD              20
     7788 SCOTT             20
     7566 JONES             20
8 rows selected.