[Resolved] Conceptual db planning

[jonki]

Hi,

I am currently writing a data base and I have certain concepts in my head and I was wondering if anyone could point out any flaws in my planning.

I am writing a web based search engine for automobiles in a certain region. The datebase stores all the details and the user can post entries or view them selecting certain search criteria.

My plan is to have 2 (main) tables in my data base - one for private sellers who pay nothing, and one for dealers who have to pay. When someone does a search it searches both tables equally.
The reason I have for splitting it into two is because dealers can enter as many cars as they like (as they pay for - better said) and the private person can only enter 1 car. Also as the dealers are paying it makes better sense (in my mind) to have them in a separate table.

Is this common practice? I haven't seen any examples of people searching two tables equally - is this bad planning?

Would it be a better idea to have one table with a separate column to identify which are dealers and with are not?

Any one had (has) similar projects they could point out any pitfalls?

I already have one table up and running but before I incoroprate my second table - it would save me a hell of a lot of time if some one set me right right at the begninning.

Thanks a lot.

[AstroTeg]

Typically, when you're designing tables, you want like (or very similar) data to be together.

If you have a table full of cars, it doesn't make sense to have 2 tables full of cars, especially if both contain practically the same amount of info.

To go even deeper, you'll find there's only about 20-30 manufactures. Repeating these same manufactures all the time gets repeatitive and you're chewing up database storage. So create an automobile manufactures table and link the car table to the manufactures table via ID.

For the dealers and users, you may find their info is very similar as well - except one has paid you money. You might decide to go with a flag that says if the user is a dealer or a private person. Or use another table (one that stores transactions or something).

Just ideas. But I'd keep the like data all together. Its what makes databases so useful. Searching 1 table is a ton easier than trying to search 2 tables.

[jonki]

Thanks a lot - that has cleared up a lot of thinking!

I did some planning based on your advice and what I thought was going to be complicated (or impossible) to do in one table - I think I've worked out a way.

Thanks

Jon