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The special characteristics of the
AutoNumber field (automatic generation, uniqueness, the fact that it cannot be changed, and so
on) make it the ideal candidate fore primary keys. Furthermore, an AutoNumber value is nothing
more than a 4-byte integer value, making it very fast and easy for the database engine to manage.
For all of these reasons, the Access Auto Auction exclusively uses AutoNumber fields as primary
keys in its tables.
You may be thinking that all these sequence numbers make it hard to look up information in your
tables. Just remember that, in most case, you never look up information by an ID field. Generally,
you look up information according to the purpose of the table. In the tblContacts table, for
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Designing Bulletproof Databases 3
example, you would look up information by customer name??”last name, first name, or both.
Even when the same name appears in multiple records, you can look at other fields in the table
(zip code, phone number) to find the correct customer.


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