What good is a table that has no primary key? In 20 years of designing databases large and small I cannot recall a single case where it would have been appropriate having a table without primary key.
Just consider the following scenario: for some reason (eg programmatic error) an identical record is inserted twice. You want to get rid of one copy. Unless you use a backend that generates some sort of unique feature (eg OID in PostgreSQL) you will find that you can't.
Horst
Oracle Applications does not use referential integrity amongst its tables, for one. The overhead for RI in some cases can be...excessive. Which is one thing, in an odd way, that probably *helps* MySQL be a tolerable DBMS behind applications, despite its deficiencies and warts. Most web app developers seem to implement and enforce RI in their applications...
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