Consider SQL queries Q1, Q8, Q1B, and Q4 in Chapter 4 and Q27 in Chapter 5.
a. Draw at least two query trees that can represent each of these queries. Under what circumstances would you use each of your query trees?
b. Draw the initial query tree for each of these queries, and then show how the query tree is optimized by the algorithm outlined in Section 19.7.
c. For each query, compare your own query trees of part (a) and the initial and final query trees of part (b).