Using store procedure within sql statement?

Question

I have the following sample tables:
project id project_name
====== ===============
1          project one
2          project two
3           project three
employee_id     fname          lname
=========== =============     =====
100          amy          A
200          better          B
300          carrie          C
project_id     employee_id
===========     ===========
1          200
2          300
3          100
there is a procedure getFullname(empployee_id) in place that combines the fname with lname to full name
what i need to accomplish is the following.
project is created by employee
==============================
project one is created by better b
project two is created by carrie C
project three is created by amy A
but the rule is: you have to call the procedure getFullName(employee_id) to accomplish the task above, and don't use the join tables to get the full employee name

Answer 1

CREATE OR REPLACE FUNCTION YOUR_FUNCTION(i_nEmpId IN NUMBER)
RETURN VARCHAR2 IS
BEGIN
  RETURN 'Lastname ' || TO_CHAR(i_nEmpId) || ' Firstname';
END;
WITH PROJECTS AS (SELECT 1 PROJECT_id, 'project one' PROJECT_NAME FROM DUAL
                  UNION ALL
                  SELECT 2 PROJECT_id, 'project two' PROJECT_NAME FROM DUAL
                  UNION ALL
                  SELECT 3 PROJECT_id, 'project three' PROJECT_NAME FROM DUAL
  PROJ_TO_EMP AS (SELECT 1 PROJ_ID, 100 EMP_ID FROM DUAL
                  UNION ALL
                  SELECT 2 PROJ_ID, 200 EMP_ID FROM DUAL
                  UNION ALL
                  SELECT 3 PROJ_ID, 300 EMP_ID FROM DUAL
SELECT PROJECT_ID,
       PROJECT_NAME,
       EMP_ID,
       YOUR_FUNCTION(EMP_ID),
       PROJECT_NAME || ' is created by ' || YOUR_FUNCTION(EMP_ID)
  FROM PROJECTS,
       PROJ_TO_EMP
WHERE PROJECT_ID=PROJ_ID;