The order of execution (of PL/SQL function calls) changes...why??

Question

select e.EMPID empid,
e.name name,
aatest.SETVALUES(2) z,
aatest.TEST1() b,
aatest.TEST2() x,
aatest.TEST3() y
from emp e
where e.empid = 101
order by e.name;
when I execute this select statement...the order of function calls is as follows:
setvalues 1st (call no:1)
test1 (call no:2)
test2 (call no:3)
test3 (call no:4)
Now...I introduce a join between the two tacles as mentioned in the query
select e.EMPID empid,
e.name name,
e2.deptno deptid,
aatest.SETVALUES(2) z,
aatest.TEST1() b,
aatest.TEST2() x,
aatest.TEST3() y
from emp e, emp2 e2
where e.empid = e2.empid
order by e.name;
The order of execution of function calls changes to
(I observed this using DBMS_OUTPUT.PUT_LINE)
test3 (call no:1)
setvalues 1st (call no:2)
test1 (call no:3)
test2 (call no:4) (the first and last calls swap!)
i.e: it calls the last function in the select statement at the beginning
instead of calling it at the last. Is it the normal behaviour? or whats going on
here?
Can somebody explain me, please....
Details:
the following four functions are defined in a package called 'aatest' and compiled.
aatest.SETVALUES(2)
aatest.TEST1()
aatest.TEST2()
aatest.TEST3()
the Tables EMP and EMP2 are two tables defined in the same schema.

Answer 1

Your "thinking" is wrong here. You can not use the column order to model your program flow. As SQL is set/tupel based, there is no given sequence of the execution order. Otoh you want to have a specific order in wich your functions must be executed otherwise the result will be wrong (or undefined). Thus here you need a procedural approach. This can be done by using PL/SQL for example.
You would code your functions in that way, that they are working correctly independent from the place where they are called ie if function1 needs the setvalues function, this function must be called inside the function1 then.
Are you sure you need all these functions in this procedural approach inside the sql-statement? This is mostly not needed and can be accomplished by using pure SQL. If not, may be your design is broken.