Sequence of execution

Question

Hello to every body
I need to know about sequence of execution in a select command.
I have a sql command that use a function.some thing like:
select id, function(item)
from tbl
where conditions...
I want to know that if my function on item execute before where section or vise versa.
I try to explain it more. I want to know that sql engine fetch rows according to where clause and then execute my function or execute my function and then fetch the rows according to where clause.
If you have a document or some thing that explain about sql engine and sequence of execution please let me know.
Your help is really appreciated.

Answer 1

EXPLAIN PLAN SET STATEMENT_ID='TSH' FOR
SELECT *
FROM emp e, dept d
WHERE e.deptno = d.deptno
AND e.ename = 'SMITH';
SELECT *
FROM TABLE(DBMS_XPLAN.DISPLAY('PLAN_TABLE','TSH','BASIC'));
for this u need to have PLAN_TABLE in your schema
Regards,
Abu