"other people will want access".  Could you be a little more specific as to whether you intend to provide access to those people?

There is a cost to cleaning up: determining what data you need to keep and what is safe to throw away.  Unless the clean up is a habit ingrained into...

Good question. I missed the effect of DISTINCT in the AVG aggregation, but as previously stated, the answer didn't change for the values provided.   A better challenge would be...