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Data Warehouse Nulls

P: n/a
Hello..

I was wondering if anyone out there could tell me how they deal with
NULL values in a data warehouse? I am looking to implement a warehouse
in SQL 2005 and have some fields which will have NULL values and I
would like some further ideas on how to deal with them. At my last job
in dealing with Oracle we were just going to leave the fields NULL, but
in SQL how would you best recommend cleaning the data? I greatly
appreicate your help and look forward to your reponses.

Thank you

Mar 15 '06 #1
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2 Replies


P: n/a
Very interesting question. The answer is "it depends."

As a general rule, I'll leave money as null usually. My logic is that
if a dollar amount is unknown, that is different then the dollar amount
zero, and i probably need to deal with the unknowns wherever and
whenever the amounts are shown to teh end user. This leads to
interesting discussions with the users, as you get to explain to them
the issues, and ask them what they want the defaults to be, or whether
they want to skip the data, and how they want the reports to be
documented.

For text fields, I will usually convert to ' '. Olap likes that
better. Sometimes I will convert nulls to 'BLANK'. Just kind of
depends.
Dates need to stay null. A null date is the easiest thing to deal
with.

Does this answer your questions? Are you doing OLAP? You might try
creating a cube with your denormalized data. OLAP is pretty neat for
datawarehouses where users want to extract data.
Regards,
Doug

Mar 15 '06 #2

P: n/a
Thanks so much Doug! Your answer is of great help!

Mar 15 '06 #3

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