Passing field name into Cursor

Question

I would like to pass the name of a field for the WHERE clause, into a cursor. In my application I need to change the field name for the where clause. I get an "Invalid Number" error when I try the following:
cursor l_sel2Cur (c_group varchar2)
is
select email from test_grp_tbl6 where c_group = 1;
select column_name
into l_colName
from listserv_grp_lk
where lg_id = v_listserv_grp;
open l_sel2Cur(l_colName);
I hope this is enough explanation. I have seen examples where the value for the where clause is passed in, but not where the field name itself is passed in. Is this possible?
Thanks in advance,
John

Answer 1

See the following example:
SQL> create or replace procedure print_enames(in_col in varchar, in_val in varchar2) is
  2  c sys_refcursor;
  3  v_name emp.ename%type;
  4  begin
  5    open c for 'select ename from emp where '||in_col||'='''||in_val||'''';
  6    loop
  7     fetch c into v_name;
  8     exit when c%notfound;
  9     dbms_output.put_line('ename='||v_name);
10    end loop;
11  end;
12  /
Procedure created.
SQL> select * from emp;
     EMPNO ENAME      JOB              MGR HIREDATE         SAL       COMM     DEPTNO
      7369 SMITH      CLERK           7902 17-DEC-80        800                    20
      7499 ALLEN      SALESMAN        7698 20-FEB-81       1600        300         30
      7521 WARD       SALESMAN        7698 22-FEB-81       1250        500         30
      7566 JONES      MANAGER         7839 02-APR-81       2975                    20
      7654 MARTIN     SALESMAN        7698 28-SEP-81       1250       1400         30
      7698 BLAKE      MANAGER         7839 01-MAY-81       2850                    30
      7782 CLARK      MANAGER         7839 09-JUN-81       2450                    10
      7788 SCOTT      ANALYST         7566 19-APR-87       3000                    20
      7839 KING       PRESIDENT            17-NOV-81       5000                    10
      7844 TURNER     SALESMAN        7698 08-SEP-81       1500          0         30
      7876 ADAMS      CLERK           7788 23-MAY-87       1100                    20
      7900 JAMES      CLERK           7698 03-DEC-81        950                    30
      7902 FORD       ANALYST         7566 03-DEC-81       3000                    20
      7934 MILLER     CLERK           7782 23-JAN-82       1300                    10
14 rows selected.
SQL> set serverout on
SQL> exec print_enames('mgr','7839')
ename=JONES
ename=BLAKE
ename=CLARK
PL/SQL procedure successfully completed.
SQL> exec print_enames('sal','1250')
ename=WARD
ename=MARTIN
PL/SQL procedure successfully completed.
SQL> exec print_enames('deptno','30')
ename=ALLEN
ename=WARD
ename=MARTIN
ename=BLAKE
ename=TURNER
ename=JAMES
PL/SQL procedure successfully completed.