[thelist] Newbie - DB Design Help

[Ken Schaefer]

The bid field appears to be completely redundant in the schema you have
below. You could achieve the same by simply having a composite PK that
consists of the dept_Id and product_Id fields, which would be truer to 3rd
normal form

Cheers
Ken

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: -----Original Message-----
: From: thelist-bounces at lists.evolt.org [mailto:thelist-
: bounces at lists.evolt.org] On Behalf Of Rob Smith
: Sent: Saturday, 29 July 2006 1:45 AM
: To: thelist at lists.evolt.org
: Subject: Re: [thelist] Newbie - DB Design Help
: 
: <snip>Generally your entities will become tables. Where entities have a
: M:N (Many:Many) relationship, you will need a "bridging" table. If you
: do up your ER model first, your database schema (at least in 3rd normal
: form) writes itself.</snip>
: 
: Yup. I agree that you disagree with me. You actually answered my next
: post about the best way to rethink this approach:
: 
:                       Bridge_Dept_Prod
:    Deptarments      ---------------------
: ----------------    bid         int 4  PK          Products
: dept_id int 4 PK => dept_id     int 4  FK    -------------------
: ...                 product_id  int 4  FK <= product_id int 4 PK
:                                              ...
: 
: Yes, the bad and the good news here is that you get to effectively
: micromanage the relationships in order to have a many-to-many
: relationship.