CS145 - Spring 2004
Introduction to Databases

Gradiance XPath and XQuery Labs
Due Thursday April 29

This week, in addition to some regular Gradiance exercises, you will be using the Gradiance Lab feature again -- this time to perform XPath and XQuery exercises. The queries you write will be executed over stored XML documents and checked automatically for correctness. When you log into Gradiance to complete this week's assignment, you will need to choose both Lab Projects and Homeworks to complete your work. Note that you have until Thursday (not Tuesday) to complete this week's work.

You have two XPath/XQuery Labs to complete: one called University and one called Auctions. Although both labs have a mix of queries, we suggest you start with the lab called University first. Here are some suggestions -- the first is new, while the second and third are repeats from last week's SQL labs:

You will probably find XPath and XQuery problems quite difficult to get absolutely right with the first (or second, or third, ...) try. We suggest you build up your queries in pieces. Obviously your initial small pieces will not yield correct answers according to Gradiance, but the answers (or syntax errors!) that you get should help you build up to that final correct solution.
Each lab allows you to submit solutions for all of the queries in the lab at one time. However, we suggest that you work on one query at a time until you get it correct. The queries in each lab are ordered roughly from easiest to hardest, but you're welcome to work on them in any order you like (or all at once if you prefer).
We strongly suggest that you maintain a separate file containing the text of your queries as you develop your solutions. This file may be of use to you during your session, and is especially important across sessions and in the event that you lose your Gradiance session for some reason.

As always, your Gradiance work is due at 11:59 PM on the due date, and no late work is accepted -- the labs will not be available after 11:59 PM on the due date.

Support Materials

Gradiance uses Quip to execute queries in XPath and XQuery over XML documents. Since XPath and XQuery are not nearly as mature and standardized as SQL, there are a number of dialects and quirks. It is VERY IMPORTANT that you look over our XPath and XQuery Help Document before getting started, and keep it handy as you work. You may well tear your hair out if you don't.

Getting Help

If questions or issues arise as you are working with Gradiance, please contact the course staff at cs145@cs.stanford.edu. The Gradiance support address (support@gradiance.com) is NOT to be used for logistical questions about the assignment, or for technical questions about the XPath/XQuery languages or the Quip system. Please use the Gradiance support address only in the case of a major failure of the Gradiance system itself. Even then we suggest you contact the course staff first, before contacting Gradiance.

Launch Gradiance to get started.