CS 6360.MS1.  Database Design
Spring 2017
Assignment 4
Sat, Mar 11

Due: Fri, Mar 24 (on elearning).

Optimize the following SQL query on the Company Database to find
names of employees earning over $30,000 per year, names of projects
on which they work more than 12 hours per week, among projects that
are located in Houston.

   Select E.lname, E.fname, P.pname, W.hours
   From   project P, employee E, works_on W
   Where  E.ssn = W.ssn
     and  W.pno = P.pno
     and  P.plocation = 'Houston'
     and  W.hours > 12
     and  E.salary > 30000

Start with an initial query tree generated by the parser that uses
left associativity for joins.  Show the query tree after each major step
of the algorithm.  Show the query execution plan of the optimized query.