Joe,
Add a generated PK to the time dimension. The PK is stored
as an FK in the fact table.
That way you can select from the time dimension by year, day, qtr,
whatever,
and easily pick out the correct fact table rows.
"The Data Warehouse Lifecycle Toolkit" includes a spreadsheet to generate
the DDL/DML for a very robust time dimension. I think it has about 20
columns.
Very good book, can't recommend it enough.
Jared
Joe Testa <[EMAIL PROTECTED]>
Sent by: [EMAIL PROTECTED]
05/20/2002 04:08 PM
Please respond to ORACLE-L
To: Multiple recipients of list ORACLE-L <[EMAIL PROTECTED]>
cc:
Subject: Data Warehouse experts, a simple question for you
Ok i'm messing with dimensions.
dm_time to be exact:
create table dm_time
( calendar_date date not null,
calendar_month number(2) not null,
calendar_qtr number(1) not null,
calendar_year number(4) not null);
insert into dm_time values(to_date('20020101','YYYYMMDD'), 1,1,2002);
insert into dm_time values(to_date('20030101','YYYYMMDD'), 1,1,2003);
2 rows nice and simple
trying to validate the dimension comes up with an error, my guess is
because of the design of the table
where basically calendar_date is child of
calendar_month is child of calendar_qtr is child of calendar_year,
wont validate.
- the question i have is this, should month really be like 2002-01 with
the year included, likewise with qtr, then it
will validate ok.
Was the design of dm_time just dont wrong or am i missing something here.
thanks, joe
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