I'll admit I may be ignoring some of the details, but I think the essence of the question is how to avoid a cartesian product when left joining to multiple...

casey-172678 (10/4/2012)

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It looks to me like your example counts the last day in a consecutive day grouping as a visit. Here are some wrinkles:

First, your data are pure dates....

Hi Tom,

I was also confused about whether the 3NF example was in 2NF or not.

I had just submitted a really long question, but then saw your reply to James:

There's nothing...