Can a procedure in select return more of 1 value

Question

Is it possibile write a procedure called from a SELECT that return 2 value?
For ex:
SELECT proc_a (par1,par2, ret1,ret2) from xtable
where ret1 and ret2 are value returned from proc_a
Thanks

Answer 1

Well it goes something like this. However you need to remember that joining in SQL may be considerably more efficient than calling PL/SQL functions, plus you should pay attention to how many times the function actually gets called in different scenarios (I report this via a call to DBMS_OUTPUT.PUT_LINE).
Oracle Database 10g Express Edition Release 10.2.0.1.0 - Production
SQL> CREATE OR REPLACE TYPE ot_dept AS OBJECT (
  2     deptno NUMBER (2),
  3     dname VARCHAR2 (14),
  4     loc VARCHAR2 (13));
  5  /
Type created.
SQL> CREATE OR REPLACE FUNCTION f_dept (
  2     p_deptno IN dept.deptno%TYPE)
  3     RETURN ot_dept
  4  IS
  5     o_dept ot_dept;
  6  BEGIN
  7     DBMS_OUTPUT.PUT_LINE ('f_dept (' || p_deptno || ')');
  8
  9     SELECT ot_dept (d.deptno, d.dname, d.loc)
10     INTO   o_dept
11     FROM   dept d
12     WHERE  d.deptno = p_deptno;
13
14     RETURN o_dept;
15  END f_dept;
16  /
Function created.
SQL> SET SERVEROUTPUT ON;
SQL> SELECT e.empno, e.ename, e.job,
  2         e.d.deptno, e.d.dname, e.d.loc
  3  FROM  (SELECT e.empno, e.ename, e.job,
  4                f_dept (e.deptno) d
  5         FROM   emp e
  6         WHERE  job = 'CLERK') e;
     EMPNO ENAME      JOB         D.DEPTNO D.DNAME        D.LOC
      7369 SMITH      CLERK             20 RESEARCH       DALLAS
      7876 ADAMS      CLERK             20 RESEARCH       DALLAS
      7900 JAMES      CLERK             30 SALES          CHICAGO
      7934 MILLER     CLERK             10 ACCOUNTING     NEW YORK
f_dept (20)
f_dept (20)
f_dept (20)
f_dept (20)
f_dept (20)
f_dept (20)
f_dept (30)
f_dept (30)
f_dept (30)
f_dept (10)
f_dept (10)
f_dept (10)
SQL> SELECT e.empno, e.ename, e.job,
  2         e.d.deptno, e.d.dname, e.d.loc
  3  FROM  (SELECT /*+ NO_MERGE */ e.empno, e.ename, e.job,
  4                f_dept (e.deptno) d
  5         FROM   emp e
  6         WHERE  job = 'CLERK') e;
     EMPNO ENAME      JOB         D.DEPTNO D.DNAME        D.LOC
      7369 SMITH      CLERK             20 RESEARCH       DALLAS
      7876 ADAMS      CLERK             20 RESEARCH       DALLAS
      7900 JAMES      CLERK             30 SALES          CHICAGO
      7934 MILLER     CLERK             10 ACCOUNTING     NEW YORK
f_dept (20)
f_dept (20)
f_dept (20)
f_dept (20)
f_dept (30)
f_dept (10)
SQL> CREATE OR REPLACE TYPE ntt_dept AS TABLE OF ot_dept;
  2  /
Type created.
SQL> SELECT e.empno, e.ename, e.job,
  2         d.deptno, d.dname, d.loc
  3  FROM   emp e, TABLE (ntt_dept (f_dept (e.deptno))) d
  4  WHERE  e.job = 'CLERK';
     EMPNO ENAME      JOB           DEPTNO DNAME          LOC
      7369 SMITH      CLERK             20 RESEARCH       DALLAS
      7876 ADAMS      CLERK             20 RESEARCH       DALLAS
      7900 JAMES      CLERK             30 SALES          CHICAGO
      7934 MILLER     CLERK             10 ACCOUNTING     NEW YORK
f_dept (20)
f_dept (20)
f_dept (30)
f_dept (10)
SQL>