Avoid calling procedure in cursor loop

Question

Hi all,
The following sample procedure written in cursor loop,The procedure is called each and every time until the cursor loop ends..
procedure proc_main is
DECLARE
cursor c1 is
    select e.empno empno
           ,e.ename ename
           ,d.dname dname
           ,d.loc   loc
    from emp e,dept d
    where e.deptno = d.deptno ;
BEGIN
  for i in c1 LOOP
   proc_test(i.empno,i.ename,i.dname,i.loc) ;
   end loop;
END;
PROCEDURE proc_test (p_empno,p_ename,p_dname,p_loc) is
begin
select * into v1,v2,v3 ..
  from temp_tab
   where col1 =p_empno
end;What would be the alternate methods to write the above procedure instead of calling the procedure inside the cursor for loop
My idea is to use collections ..could you give me the sample code using collections to achieve the above criteria
Thank You
Edited by: smile on Feb 28, 2012 3:45 PM

Answer 1

The ideal would be to gather all of the SQL logic and put as much of it into a single SQL statement as possible. It would also be ideal to determine what the final outcome of the procedure is and use that as a starting point for your SQL. For example, if the desired outcome is to UPDATE employee salaries where they have an entry in table x, you might find that you can avoid needing to split the logic between multiple procedures i.e. instead of
procedure proc_main is
DECLARE
cursor c1 is
    select e.empno empno
           ,e.ename ename
           ,d.dname dname
           ,d.loc   loc
    from emp e,dept d
    where e.deptno = d.deptno ;
BEGIN
  for i in c1 LOOP
   proc_test(i.empno,i.ename,i.dname,i.loc) ;
   end loop;
END;
PROCEDURE proc_test (p_empno,p_ename,p_dname,p_loc) is
begin
select * into v1,v2,v3 ..
  from temp_tab
   where col1 =p_empno
    UPDATE
        emp e
    SET
        sal = v2
    WHERE
        e.empno = p_Empno;
end;You could simply have
procedure proc_main is
BEGIN
    UPDATE
        emp e
    SET
        sal = ( SELECT
                    t.new_sal
                FROM
                    temp_tab t
                WHERE
                    t.empno = e.empno
    WHERE
        EXISTS
            (   SELECT
                    NULL
                FROM
                    temp_tab t
                WHERE
                    t.empno = e.empno
END;Even if your logic is more complex than this, you're likely to find that you can merge together many of the statements that you'd be executing in a loop and replace that loop with a join.
Given the specific structure of what you have posted though, instead of calling the procedure in a loop, you could simply pass the cursor c1 as a parameter to proc_test i.e.
procedure proc_main is
    lc_c1   sys_refcursor;
BEGIN
    OPEN lc_c1 FOR
    select e.empno empno
           ,e.ename ename
           ,d.dname dname
           ,d.loc   loc
    from emp e,dept d
    where e.deptno = d.deptno ;
   proc_test(c1) ;
END;
PROCEDURE proc_test (p_Cursor sys_refcursor) is
begin
    LOOP
        FETCH ....
        ...DO SOMETHING...
        EXIT WHEN p_Cursor%NOTFOUND;
    END LOOP;
    CLOSE p_Cursor;
END;But I would strongly recommend that you consider trying to merge as much of your SQL together before you consider the cursor approach.
HTH
David