Re: Database design, replacing null by a default value

Properly formulated, a DW only reports on what happened, and ignores what did not happen.
If it's really like a DW then you just leave the nulls out. You should do this if you can.

Otherwise you have to decide how to lie based on least harm to aggregates. If you average or sum you should use 0 to avoid messing up the sums. If you can use a conditional code to skip a negative, and the negative is not allowed, -1 makes a good null, but you wouldn't want to sum it into an account or anything. Blanks may be an option depending on how Seibel interperets them, but it's probably a coding error.

For a varchar I'd use a zero-length string or a single blank, if zero-length isn't allowed. If blanks are significant, first shoot your source system designer, then use '<NULL>'. :)

paquette stephane wrote:

> Hi,
>
> We're in the process of writing functionnal specs for
> a system which is like a DW but instead of a DW the
> staging area push the data in Siebel.
>
> If we replaced null by something else.
> What would you choose :
> for a varchar field ?
> for a numeric field ?
>
> Someone has proposed blanks for the character field
> but I'm not comfortable with that.
>
> TIA
>
> =====
> Stéphane Paquette
> DBA Oracle et DB2, consultant entrepôt de données
> Oracle and DB2 DBA, datawarehouse consultant
> stephane_paquette_at_yahoo.com
>
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