CS 338: Computer Applications in Business: Databases

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1 CS 338: Computer Applications in Business: Databases Spring 207 Midterm Exam Section 00 June 9, 207 0:00am :5am. There are 0 pages in this booklet, including this cover page. Please make sure that you have no missing pages. 2. This exam consists of 4 questions. 3. You have 75 minutes to answer the questions in this midterm. 4. During the exam, you cannot refer to any books or notes. 5. Print your first name, last name and student id in the space below. Good luck! First ame: Last ame: Student ID: Q Q2 Q3 Q4

2 . Briefly answer the following questions: a) What is a Binary Large Object (BLOB)? ( pt) It is a variable-length bitstring data type that is available to specify columns that have large binary values, such as images. b) What is a candidate key? ( pt) It is a key (set of attributes which is unique) only in the cases when a relation schema has more than one key. One of the candidate keys is selected to be a primary key. c) What is a database? ( pt) It is a logically coherent collection of related data that can be recorded and that can have implicit meaning. d) How are multivalued attributes mapped onto the relational model? (3 pts) Each multivalued attribute is a new relation which includes the attribute corresponding to the multivalued attribute plus the primary key K of the relation that represents the entity type or relationship type that contains the multivalued attribute. The primary key of the new relation is the combination of the multivalued attribute and K (the primary key of the other relation). K is a foreign key of this relation referencing the primary key of the relation that contains the multivalued attribute. e) What is a disjoint specialization? ( pt) Specialization in which its subclasses are disjoint sets. This means that an entity can be a member of at most one of the subclasses of the specialization. f) What is an entity integrity constraint? ( pt) It states that no primary key value can be ULL. g) What does the CASCADE option mean in SQL Data Definition Language (DDL)? ( pt) The CASCADE option propagates the update/ deletion by updating/deleting tuples that reference the tuple that is being deleted. 2

3 h) What is a composite attribute in an ER model? ( pt) It is an attribute that can be divided into smaller subparts, which represent more basic attributes with independent meanings. i) Who are casual database end users? ( 2 pts) They occasionally access the database, but they may need different information each time. They use a sophisticated database query interface to specify their requests and are typically middle- or high-level managers or other occasional browsers. j) What is an inner join in SQL? ( pt) It is a type of join where a tuple is included in the result only if a matching tuple exists in the other relation. k) What is a total participation of an entity type in a relationship type? ( pt) It specifies that every entity from the entity type must participate in the relationship type. l) What is the notation for a key in the Entity-Relationship (ER) model? ( pt) A key is underlined attribute in an ER model. m) What is a foreign key? What is the domain of a foreign key? (2 pts) Foreign key specifies a referential integrity constraint between two relational schemas. It is a set of attributes of one relation that reference the primary key attributes of another relation. It has the same domain as the domain of the primary key attributes it references. n) What is an alternative way of modeling a ternary relationship type in an ER model? (3 pts) The relationship can be represented as a weak entity type, with three identifying relationships. The three participating entity types are the owner entity types. An entity in this weak entity type is identified by the combination of its three owner entities. 3

4 2. Consider the following relations: CUSTOMER (Customer_id, ame, Birth_date, , City, Province) TICKET (Ticket_id, C_id, Concert_id, Price, Purchase_date) COCERT (Id, ame, Artist, Concert_time, Concert_date, Location) where primary keys are underlined, TICKET.Concert_id is a foreign key to COCERT.Id, TICKET.C_id is a foreign key to CUSTOMER.Customer_id. For each part of this question (considered independently of the other parts), write a single SQL statement that accomplishes the given requirements. a) For each customer, list the customer id and the number of purchased tickets on 7 June 207. (6 pts) SELECT Customer_id, COUT(*) FROM TICKET, CUSTOMER WHERE Customer_id=C_id AD Purchase_date= 7/06/207 GROUP BY Customer_id b) Find distinct names of concerts for which customers, whose names are Jack Brown and who live in the province of Ontario, have purchased tickets. (4 pts) SELECT DISTICT COCERT.ame FROM COCERT, TICKET, CUSTOMER WHERE CUSTOMER.ame= Jack Brown AD Province= O Id=Concert_id AD Customer_id=C_id 4

5 c) Find the s and addresses of all customers who have spent more than 300 (in total) for tickets to the concert The Best Jazz Festival. Order the results by the field in alphabetical order. (7 pts) SELECT Customer_id, , City, Province FROM CUSTOMER, COCERT, TICKET WHERE Concert_id = Id AD Customer_id=C_id AD COCERT.ame= The Best Jazz Festival GROUP BY Customer_id HAVIG SUM(Price)> 300 ORDER BY d) Find the name of concerts for which every customer, who lives in Waterloo, has purchased a ticket. (8 pts) SELECT COCERT.ame FROM COCERT WHERE OT EXISTS ( ( SELECT Customer_id FROM CUSTOMER WHERE City= Waterloo ) EXCEPT ( SELECT C_id FROM TICKET WHERE Concert_id=COCERT.Id)) 5

6 e) Declare the relation CUSTOMER in SQL, such that Customer_id is an integer number, ame has up to 30 characters, Birth_date is a date, has up to 22 characters City has up to 5 characters and Province has exactly 2 characters. Every customer must be at least 8 years old on today s date. (5 pts) CREATE TABLE CUSTOMER ( Customer_id IT OT ULL, ame VARCHAR(30), Birth_date Date, VARCHAR(22), City VARCHAR(5), Province CHAR(2), PRIMARY KEY (Customer_id), CHECK (Birth_date <= 9/06/999 ) ) 3. Consider the following partial ER model for a company that organizes events (given on the next page). Modify the model to accommodate the following specifications, showing all the changes on the model itself. (25 pts) a) The database keeps track of three types of persons: customers, guests and staff. A person can belong to one, two or all three of these types. Each person has a unique id and name. Every customer has an and address, every guest has a type and every staff member receives a salary. b) Every guest is assigned to exactly one seat. A seat cannot be assigned to more than one guest. Each seat has a seat number, which is unique for a table. A seat must belong to one table and a table may contain multiple seats. c) Each guest participates in exactly one event, while each event has at least guest. d) Every customer can choose multiple menu packages, and a menu package is offered to all the customers. Each menu package contains multiple menu items. 6

7 CUSTOMER STAFF M ORGAIZES ORGAIZES SERVES EventID ame Table_no Date EVET Time TABLE Price PackageID Quantity Details MEU_PACKAGE Figure 7

8 Person_id PERSO ame o Address E_mail Salary CUSTOMER Type STAFF CHOOSES PART_OF M ORGAIZES GUEST PARTICIPATES IS_ASSI GED Seat_no SEAT M ORGAIZES SERVES BELOGS_TO EventID ame Table_no Date EVET Time TABLE Price PackageID Items Quantity Details MEU_PACKAGE 8

9 4. Create a relational model for the ER diagram you completed in Question 3. (25 pts) PERSO ID ame STAFF GUEST ID Salary CUSTOMER ID Type EventID Seatum Tableum ID Address TABLE Table_no EVET Event_ID Time Date ame Customer_id Table_num SEAT Seat_num SERVES StaffID Tableum MEU_PACKAGE PackageID Price Quantity CHOOSES MEU_ITEMS Package_ID Customer_ID Package_ID Menu_item 9

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The DBMS accepts requests for data from the application program and instructs the operating system to transfer the appropriate data.

The DBMS accepts requests for data from the application program and instructs the operating system to transfer the appropriate data. Managing Data Data storage tool must provide the following features: Data definition (data structuring) Data entry (to add new data) Data editing (to change existing data) Querying (a means of extracting