2 reasons.
1. Performance is hit.
2. Every time you make a query joining that table you must now refer to 2
columns. This makes the join slower for the engine to utilise.
3. Conjugate keys add unneccessary complexity to your code.
So why not allocate a base number to each site and offer a range of ID's
starting at that base number OR
if the sites all connect regularly, then why not use temporary ID's allways
< 0 then when ever a connection to your "Home" site is made, allocate
permenant ID's.
What ever, making you PK an integer on a single column is seriously faster
and easier to use. Often, the PK will carry no data information value. Its
PRIMARY purpose is to supply uniqueness, and thus form the primary key.
Often this technique is referred to as "Surrogate Key"
Cheers,
Tony.
-----Original Message-----
From: Leo Ramakers <[EMAIL PROTECTED]>
To: Multiple recipients of list database <[EMAIL PROTECTED]>
Date: Friday, 3 September 1999 10:01 PM
Subject: Re: [DUG-DB]: how do I use paradox composite keys
Tony
> I havent followed this thread, but it is not good practise to use
conjugate
> PK's on any database.
Can you say why?
> Master table should have an Integer PK MasterID
> Detail table should have an integer PK DetailID AND a foreign key into
> Master.
This is exactly what I have, but I need to merge a number of databases, each
with the same range of MasterID values. The 'obvious' solution to me was to
add
a site ID to the master table, include it in the masterID key, and thereby
allow
multiple master and detail tables to be merged.
regards
Leo
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