Assign a collection field name dynamically

Question

Hi
I am new to this forum. Could you please help me out with this.
I have a main collection which has 20 columns. I need to pass each of this 20 columns in another function to validate some functionality. I am thinking of doing that in naother loop. I put all thsi 20 column names in another nested table collection. I will get the column_name form the second loop. Can I combine that with the first collection to get the value of that column_name.
I will give an example wit 2 loops.
DECLARE
V_NAME VARCHAR2(100);
V1 VARCHAR2(100);
begin
for i in (select * from employeeS)
loop
for j in(select 'DEPARTMENT_ID' COLUMN_NAME FROM DUAL)
LOOP
v_name:=j.COLUMN_NAME;
v1:=i.V_NAME;
-- I need to get the value of " i.department_id "in variable v1. I need to pass the value of i.department_id (like 20 columns) to another function.
--That is the need for second loop
DBMS_OUTPUT.PUT_LINE('V1'||V1);
END LOOP;
END LOOP;
END;
This code is not compiling. It would be great ,If you can assist me with this.
My oracle version is 11g. If you need any further information, I can provide that.

Answer 1

The real question is why do you want to do this. What problem are you trying to solve?
Yes, one can create an array/collection SQL projection, as oppose to the typical projection containing scalar (single column) values. But I would be hesitant to recommend this approach as there are issues with it (such as the array only supporting a single data type), that needs to be taken into consideration.
Basic example:
// create a SQL collection/array type
SQL> create or replace type TStrings is table of varchar2(4000);
  2  /
Type created.
// use the array type to construct the SQL projection as an array of
// column values - as the array is of type string, all columns need to
// be of type string, or needs to be converted to type string
SQL> begin
  2          for c in(
  3                  select
  4                          TStrings(
  5                                  to_char(empno),
  6                                  ename,
  7                                  job,
  8                                  to_char(hiredate,'yyyy/mm/dd')
  9                          ) as COL_LIST
10                  from    emp
11                  where   rownum <= 2
12          ) loop
13                  dbms_output.put_line( '**new row**' );
14                  for i in 1..c.Col_List.Count loop
15                          dbms_output.put_line( 'col'||i||'='||c.Col_List(i) );
16                  end loop;
17          end loop;
18  end;
19  /
**new row**
col1=7369
col2=SMITH
col3=CLERK
col4=1980/12/17
**new row**
col1=7499
col2=ALLEN
col3=SALESMAN
col4=1981/02/20
PL/SQL procedure successfully completed.
SQL>