Responding to myself, I appreciate everyone's comments very much. Always good to send out a query to the internet and get thoughtful and cogent responses back! I understand...

Well, after staring at this for some time and calling in a few favors, here's my best shot of an approach that seems to work and that avoids cursors/whiles and...

I understand and agree with all your points, but if I have a million customers that have shopped on average in about 10 departments each, I'm going to be doing...

The department number field is not a bit mask but simply a number between 0 and 49 (actually 99 in the real world). My actual problem is the fact...

No, they are not just like adding, close but not exact. If I had multiple rows with the same department number, it would not work. Two records with...

The Bitwise OR is the entire reason for the logic! I am producing a bit flag of all the departments a customer has shopped at with each bit for...

The result you got is strange because on my sql server, I get 8 which is the last row that was inserted into the @Depts table. The bottom line...