Create virtual table.

Question

Hi all,
I have a table with SUBTYPE, DATAID, ORIGNALDATAID, DATE column.
select dataid, orignaldataid from table where subtype=1 and Date=01-Aug-2010.
I have the above query statment. I need the dataid for further processing, but before the processing is done. I need to check if the orignaldataid=0, if yes, dataid remains else dataid=orginaldataid. Before the list is pass to another sql. But i intend to use nested sql for futher processing, hence i need to database to crunch the data instead of using java to change the data.
I was thinking of creaating another virtaual table in DB where it will automatically do this for me instead of having dataid and orginaldatid column, it will jus have dataid column. Then i can just query this virtual table.
Select dataid from virtualTable where subtype=1 and Date=01-Aug-2010. Is it possible?

Answer 1

Hi,
If you want to have two tables
(1) your original table with all the data, and
(2) fubar, which perhaps has fewer rows, and some derived columns
and you want changes in the original table to automatically change fubar (when apppropriate), then make fubar a Materialized View . Despite the name, a materialized view is a real table. Is it auotmatically refreshed, or changed to show changes in the original table. Typically, this is done at fixed intervals, that is, you tell the system to refresh the materialized view every morning a 2:00 am, or every 30 minutes. You can also refresh it on demand, so that you know the dta is up to date.
If you are using Oracle 10, then you can't use the virtual column feature, but you can create regular columns and write triggers to populate them, based on other values in the same row. I don';t know if this would serve your needs better than a materialized view or not.