Both tables would be exactly sames apart from the foreign key relation to clients or services. I agree that it seems strange to have one column that is always null. Im using Django as my Object relational Mapper so im pretty sure I can not add a constraint such as : CHECK constraint where !(col1 IS NULL and col2 IS NULL).
Another factor ive been considering is that one of the fields in this table(s) definition(s) is free flowing text which could potentially become very large. Should I take this in to consideration when deciding whether to split the tables? In terms of searching speed that is.
On Tue, Aug 28, 2007 at 12:47:45PM +0100, Sebastian Ritter wrote: > > The update/message format is exactly the same for both. Should I make two > > different tables:
> > one table with extra columns : is_client, client_id, service_id, where > > either client_id or service_id would be null depending on the is_client > > boolean?
Is the rest of the data the same? If so, then one table is right. If not, then more than one table. In either case, I really hate the idea of two columns, one of which is always null. But if you're going to do that, make sure you add a CHECK constraint where !(col1 IS NULL and col2 IS NULL).
A
-- Andrew Sullivan | ajs@crankycanuck.ca I remember when computers were frustrating because they *did* exactly what you told them to. That actually seems sort of quaint now. --J.D. Baldwin
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