CS40 Exam #1 October 17, 2001

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1 CS40 Exam #1 October 17, 2001 Name: 1. Short answer [5 points each]: a. Consider an ER diagram giving a conceptual schema for an Amazon.com shopping basket. A basket can contain any number of items, each of which must be either a book, CD, DVD or computer game. Which of the advanced modeling concepts that we studied would be most appropriate to use in this situation? Why? (You don t actually have to draw the diagram.) b. Look ahead to question #5 on this exam. Consider FD11 and FD12. What important information is implied when we look at only these two dependencies? How can this particular bit of information be refined when we consider the rest of the dependencies as well? c. Write the query for question #6a on this exam using SQL. d. Explain using plain English one benefit of putting a relational schema into third normal form.

2 2. Draw an EER Diagram for the information system described below: The International Aquarium Society wants to keep track of all of the major aquaria in the world. Each aquarium has many tanks and each tank has many creatures in it. Each aquarium has a name and location, and each tank has a name and a location. The creatures each have a name, and are divided into fish, mammals, and reptiles. The creatures are also divided into carnivores (that eat other creatures) and herbivores (that don t). Some creatures are both carnivores and herbivores. Each creature has man-made food that it eats. We have to keep track of which creatures are eaten by which carnivores so that we can keep them in separate tanks. Identify classes A (aquarium), C (creature), F (fish), M (mammal), R (reptile), T (tank), X (carnivore), H (herbivore), Y (food). Only the attributes mentioned above need to be shown in the diagram (though there obviously should be more). Hint: I suggest ignoring the food-related modeling at first. Build your diagram without it, then make a couple of simple additions to incorporate the eating habits. [20 points]

3 3. Consider the following ER diagram, and answer the questions about it. Briefly explain the yes/no answers. [4 points each] a. May a customer hold different loans at different bank branches? b. May a customer hold different accounts at different bank branches? c. Can a prospective borrower make an early payment on a loan before it has been officially approved? d. Write sentences in English that express the roles of a loan in the diagram. e. Can the same branch administer both accounts and loans? 4. a. Convert the ER diagram from the previous question to relational schemas. Be sure to indicate all keys and foreign keys. (See question #5 for the format to use.) [15 points]

4 b. How might a DBMS like Oracle or Access enforce the must participation constraints in the diagram? Explain using a specific example from the diagram. [5 points] 5. Consider this hypothetical schema from BigHit Video: PurchaseInfo:(purchaseOrderId, supplierid, suppliername, street, city, state, zipcode, movieid, title, quantity, dateordered) and the following list of functional dependencies: FD1: purchaseorderid {supplierid, dateordered} FD2: supplierid suppliername FD3: supplierid {street,zipcode} FD4: zipcode {city,state} FD5: {street,city,state} zipcode FD6: movieid title FD7: {title,dateordered} quantity FD8: title movieid FD9: supplierid {suppliername,street,city,state,zipcode} FD10: purchaseorderid {supplierid,dateordered,suppliername,street, city,state,zipcode} FD11: {purchaseorderid,movieid} {supplierid,suppliername,street, city,state,zipcode,title,quantity,dateordered} FD12: {purchaseorderid,title} {supplierid,suppliername,street, city,state,zipcode,movieid,quantity,dateordered} a. Convert PurchaseInfo to 2NF. Briefly explain your steps. [10 points] b. Convert the relations from part (a) to 3NF. Briefly explain your steps. [10 points]

5 6. Consider the relational schemas for the student grades database given on the last page of this exam. Perform the following queries using relational algebra. [5 points each] a. List the names of instructors who taught ENG11 in the fall term of b. List the student name, student number, and grade made for students who took ENG11 in the spring term of c. List the stunum and stuname of senior CS majors who have made at least one A and at least one B. d. List the names of all courses that have no prerequisite.

6 Relational Schemas for Course and Grade Database Table Attribute Data Type Keys and custom rules Student stunum number(4) primary key specify a value range: stunum between 8 and 20 stuname varchar2(8) class number(1) custom rule: class in ( 1, 2, 3, 4 ) major varchar2(4) Course cournum varchar2( 6) primary key courname varchar2( 30) credithr number( 1) custom rule: credithr in ( 2, 4 ) dept varchar2( 4) Prereq cournum varchar2( 6) primary key and foreign key prereqnm varchar2( 6) primary key and foreign key Cournum and prereqnm together form the primary key. Separately they are foreign keys. Sections secid number( 4) primary key cournum varchar2 (6) foreign key semester varchar2( 6) acadyear number( 4) custom rule: year between 1997 and 2001 instr varchar2( 10) Grades stunum number( 4) part of primary key and a foreign key secid number( 4) part of primary key and a foreign key Stunum and secid together form the primary key. Separately they are foreign keys. grade char 1 custom rule : grade in ( A, B, C, D, F )

CS40 Exam #2 November 13, 2002

CS40 Exam #2 November 13, 2002 Name: Except where explicitly noted, all of the questions on this exam refer to the database defined by the relational schemas given on the last page of this exam. 1. For