jAustin hw6 submission

I only used 1 commit for this assignment (oops!) because I began moving from one query to the next fairly quickly. I made the datatype of amount NUMERIC instead of MONEY as I couldn't manage casting it to perform the addition in the one UPDATE call required. I also noted that with either INTEGER or NUMERIC, zipcodes with leading 0s were truncated (e.g. 02155 --> 2155). I've noticed a similar problem in GrubHub, funnily enough, but wasn't able to resolve this issue without representing zip codes as TEXT (which doesn't seem right). I was also unsure if 'blank' descriptions were an empty string or NULL, but ultimately chose to represent them as empty strings.