[snip]...Look into Codd's relational model. First order, second order, etc.


Well since you were so helpful, maybe you could help me with one additional question.

On the following URL:

http://www.utexas.edu/cc/dbms/utinfo/relmod/relmod2.html#Heading9

primary and foreign keys are defined. Noting the requirement for primary keys to be unique, follow the link to Figure 1.3 and notice the table he calls an 'allkey' table. Clearly, neither of these columns contains unique key values (though the pairs are unique) yet they are both labled as 'PK', primary key, columns?? This confuses me.

Do you know if these columns are mislabled or do you think the authour really meant that the two-member tuples of the all key table formed a unique key, or what?