Assignment 1 (15 points total, 2.5 point each) Consider the database consists of four relations (same as Figure 2.20 and 2.21 in your textbook):

1. Write the schema definition statements in SQL for these four relations. 2. Write SQL queries to answer the following questions. Making sure that duplicates are eliminated. What PC models have a speed of at least 3.00? 3. Find the maker(s) of the computer (PC or laptop) with the highest available speed. 4. Find the average price of PCs made by maker A. 5. Find the makers who sell exactly three different models of PC. 6. Delete all PCs with less than 100 gigabytes of hard disk.

rigure z.zU: sampie data ror rroauct (a) Sample data for relation PC (b) Sample data for relation Laptop (c) Sample data for relation Printer Figure 2.21: Sample data for relations of Exercise 2.4.1