Posted by Erland Sommarskog on 01/08/07 22:44

Dave (daveg.01@gmail.com) writes:
> Do you know of any book or other reference to this (specifically how
> the optimizer needs a key)? It would really help me convince everyone
> to use keys on everything.

It's not really a matter of the optimizer needing a key. Adding an
IDENTITY column is not going to change this particular problem. It's
more about database design in general. Every table in a database should
have a primary key. Preferrably this should be a natural key, but this
is not always possible. In a relational database, you access data through
data, that is the primary key.

By defining good primary keys, you can avoid duplicate data. With further
normalisation, there are more anomalies you can avoid.


--
Erland Sommarskog, SQL Server MVP, esquel@sommarskog.se

Books Online for SQL Server 2005 at
http://www.microsoft.com/technet/prodtechnol/sql/2005/downloads/books.mspx
Books Online for SQL Server 2000 at
http://www.microsoft.com/sql/prodinfo/previousversions/books.mspx

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