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RE: Design Question - Thoughts Needed

From: Mercadante, Thomas F <NDATFM_at_labor.state.ny.us>
Date: Mon, 25 Jun 2001 10:19:49 -0700
Message-ID: <F001.00336DB4.20010625101818@fatcity.com>

Tracy,

I would fight tooth and nail for a separate auto_coverage table that is a child to each parent auto record. (It actually represents a many-to-many relationship between the auto table and the available_coverage table which lists all coverages available).

When you argue about performance problems during reporting, it pales in comparison to performance problems if, say, the coverage name changes, or if you want to know "Who/how many people have just towing". In my example, you query the child table for the coverage code that = towing. In your example, you query all parent records.

This is the real reason why normalization is required in relational design. Break everything down into it's smallest parts so you can query and update just the atomic item you need.

just my 2 cents.

Tom Mercadante
Oracle Certified Professional

-----Original Message-----
Sent: Monday, June 25, 2001 1:16 PM
To: Multiple recipients of list ORACLE-L

We are looking to redesign our current system and a question popped up that I
am struggling with. (our business is auto insurance). Each vehicle on a policy may have 1 or many coverages. For example, comprehensive, collision,
towing, property damage ... A couple of things: 1- some coverages will not apply because they are state specific. 2 - some coverages will not be chosen
by the insured. Therefore, should I have a vehicle table with each coverage and its premium as separate specific columns or should I add a coverage table
which will contain the coverage and premium. Under the later example if I have
10 coverages and I want to print them on the insured's declaration page don't I
have a possible performance problem with up to 10 i/os. Where as with the first example I only have 1 read but possible space wastage. I know in 1st normal form you should remove repeating groups, in my case is a coverage a repeating group? Where do you draw the line? For example, clients may have
multiple phone numbers although I don't see many examples where the phone numbers are split into another table. Please share any thoughts that may make
my decision easier. Thanks

Just an fyi, in our current design the coverages have been stored with the vehicle.

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Author: Tracy Rahmlow
  INET: Tracy.Rahmlow_at_aexp.com

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Author: Mercadante, Thomas F
  INET: NDATFM_at_labor.state.ny.us
Fat City Network Services    -- (858) 538-5051  FAX: (858) 538-5051
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