Select * from FUNCTION(a,b,c,...)

Question

Hi,
Our client asked us not to use VIEW in our entire application!
After wasting one week negotiating with them, I am looking for some alternatives for views to simplify our complex queries.
Can I use functions instead of views in select statements? Could you give me a sample for SCOTT.EMP table? I am looking for something like:
SELECT * FROM UDF_FUNCTION(123)
Are functions a good alternative for views? What are my other options?
Regards,
Alan

Answer 1

You can select from a function if you create a "pipelined function". I would definitely use a view if I could, since a pipelined function will almost certainly not perform as well as a well-tuned view. Pipelined functions can be useful for ETL transformations, but are probably not the best choice for data access routines to deliver results to an end-user.
Anyway, here is a simple example, using the SCOTT sample schema:
SQL> create type EmpType as object
  2  (
  3  empno number(4),
  4  ename varchar2(10),
  5  sal number(7,2)
  6  );
  7  /
Type created
SQL> create type EmpTabType as table of EmpType;
  2  /
Type created
SQL> create or replace function EmpFunc(p_in_sal IN NUMBER) return EmpTabType PIPELINED IS
  2    l_emp_rec EmpType := EmpType(NULL,NULL,NULL);
  3  begin
  4    for emp_rec in (select * from emp where sal > p_in_sal) loop
  5      l_emp_rec.empno := emp_rec.empno;
  6      l_emp_rec.ename := emp_rec.ename;
  7      l_emp_rec.sal := emp_rec.sal;
  8      PIPE ROW( l_emp_rec );
  9    end loop;
10    return;
11  end EmpFunc;
12  /
Function created
SQL> select * from TABLE( EMPFUNC( 2000 ) );
     EMPNO ENAME             SAL
      7566 JONES            2975
      7698 BLAKE            2850
      7782 CLARK            2450
      7788 SCOTT            3000
      7839 KING             5000
      7902 FORD             3000
6 rows selected
SQL>