Re: Too add a new table or not

In article <YNBXIBKav+57EwfG_at_shrdlu.com>, Bernard Peek says...
>
>In message <6dae7e65.0111060408.443f57c8_at_posting.google.com>, Lennart
>Jonsson <lennart_at_kommunicera.umea.se> writes
>
>>
>>What if Student have lets say 15, and Teacher have 5 attributes. Given
>>that 2 or 3 of the attributes are common for both types, should one
>>model that with a single table, or use 1 parent table and 2 subtype
>>tables?
>
>Database design isn't only driven by the structure of the data. You
>might need to think about how the data is going to be used. How big are
>the tables? If you create a new table then you will probably need to
>write some new programs too. Can you justify the extra time to do that?
>In a large system the extra storage space for unused fields may make it
>worth optimising the system by creating extra tables.
>

I was more thinking about an initial design - and to make things simpler - only the logical model. Lets say I have identified the structures mentioned earlier, should I aim for 1 or more entities? I'm participating in a project where we have similar structures, thus interested in what is considered the apropiate thing to do.

Kind regards
/Lennart Received on Tue Nov 06 2001 - 19:04:29 CET