How to create a view with parameters; read the documentation but nothing!

Question

Hello!
I'm new to the Oracle world but together with my coworkers we need to very quickly study Oracle to figure out whether we'll add Oracle to our list of supported databases or not.
Question: How do I create a view with parameters?
I've read the documentation but I could not find this! I found the sql syntax to create a view but no parameters whatsoever...
I have found on the web some very complicated way of doing this, but doesn't Oracle support Views with parameters?
The goal here is to return a recordset, don't forget, so,please don't speak about stored procedures unless you are going to tell me how to get a recordset out of a stored procedure! ;)
Thanks for all your help and attention!
Jorge C.

Answer 1

You can set up a parameterized view via context as follows:
1. Set up a procedure to set your context values:
create or replace procedure p_set_context (p_context IN VARCHAR2,p_param_name IN VARCHAR2,p_value IN VARCHAR2)
as
BEGIN
sys.dbms_session.set_context(p_context,p_param_name,p_value);
END;
2. Create your context using the procedure you just created
create or replace context my_ctx using p_set_context
3. This is the test table I'll use
create table my_table(col1 number)
and populate it:
begin
for v_index in 1..10
loop
insert into my_table values(v_index);
end loop;
end;
and the view that will be parameterised
create or replace view v_my_table as select col1 from my_table where col1 between sys_context('my_ctx','start_range') and sys_context('my_ctx','end_range')
4. Now set the parameters using the procedure above.
begin
p_set_context('my_ctx','start_range','1');
p_set_context('my_ctx','end_range','5');
end;
5. Selecting from my_table will give you 1 to 10 (no surprise there :-) )
selectng from v_my_table will give you 1 to 5
You can use the context to set formats etc using the same principle. A common gotcha to watch for is trying to set the context directly using DBMS_SESSION.SET_CONTEXT instead of creating a procedure. This belongs to SYS and SYS won't have the privileges to set your context so you get an insufficient privileges result leading to much headscratching and unnecessary grants (at least that's my understanding of it).
Sorry Jorge, as you're new to Oracle I should also have pointed out for completeness sake, that you can change the parameters at any time through recalling the p_set_context, for example, following on from above, after your "select * from v_my_table" and seeing 1 to 5, you could then do
begin
p_set_context('my_ctx','start_range','3');
end;
and when you requery 'Select * from v_my_table' you will now see rows 3 to 5.
Bit of a simplistic example, but you can see how easy it is. :-)
Message was edited by:
ian512