Relationships

[Guest]

I understand the proper way to set up a relationalship database is to use a
primary key with a auto number in the main table and then relate the other
tables back to this number.
However, I am importing an existing data base that has a field named CODE
in each table (Main and others) with alphanumeric code such as kre222 in the
CODE field.
If I use this CODE field for my relationship points, will I have any
problems??
Thanks
George

 

[Brendan Reynolds]

There's nothing intrinsically wrong with an alphanumeric primary key. What
is important is that it must be unique, it must be non-Null, it should be
simple, and it should rarely change.

 

[Guest]

I can understand the reason for the autonumber and if I build a database from
scratch I will certainly use it, but this existing atabase is quite large and
I did not want to make major changes for no good reason. Thanks for your
help.
George

 

[Brendan Reynolds]

As long as those codes are unique, are always known, and rarely (preferably
never) change, you should be OK.

On thing to keep in mind - there are only so many possible combinations of
three characters and three digits - I make it 16,224,000 possible
combinations using letters 'a' to 'z' and numbers 000 to 999. (I'm no
mathematician, so if I got that wrong I hope someone will correct me.) If
you ever have more records than that, you'll need to add additional
characters or digits to the codes.