Copyright © 2011 by Michael V. Mannino All rights reserved. Database Design, Application Development, and Administration, 5 th Edition Quiz G4 Hyunwoo Choi Xiaobin Lin

Chapter 3: The Relational Data ModelSlide 2 1. a  Order is not matter  Each row is a unique  Primary key and foreign key

Chapter 3: The Relational Data ModelSlide 3 2. d CREATE TABLE Enrollment ( OfferNoINTEGER, StdNoCHAR(11), EnrGradeDECIMAL(3,2), CONSTRAINT PKEnrollment PRIMARY KEY(OfferNo, StdNo), CONSTRAINT FKOfferNo FOREIGN KEY (OfferNo) REFERENCES Offering ON UPDATE CASCADE, CONSTRAINT FKStdNo FOREIGN KEY (StdNo) REFERENCES Student ON UPDATE CASCADE )

Chapter 3: The Relational Data ModelSlide 4 3.  Which of the following constraints are enforced by a relational data model?  a. A value stored in a column within a row is atomic.  b. Values in a primary key column are unique.  c. Values in a foreign key column are subsets of values in a referenced  column.  d. All of the above.

Chapter 3: The Relational Data ModelSlide 5 4. Mark True or False:  a. The referential integrity rule ensures that people, things and events are uniquely identified in a database. False  b. A primary key can not be a superkey False

Chapter 3: The Relational Data ModelSlide 6 4.  c. A superkey may be designated to be a primary key. True  d. Each operator of relational algebra transforms one or more tables into a new table. True  e. Any attribute, whose values are unique in current relational database state, is a candidate key. False

Chapter 3: The Relational Data ModelSlide 7 5. a, between 0 and M*N Special case: no match in the columns we are joining

Chapter 3: The Relational Data ModelSlide 8 6. d, between 0 and M*N Special case: the rows from N matches all the rows from M

Chapter 3: The Relational Data ModelSlide 9 7. B  Table A does not have valid column ID  Table C, D are not atomic  Table E contains two values in one cell

Chapter 3: The Relational Data ModelSlide Entity integrity  Entity integrity: primary keys  Each table has column(s) with unique values  Ensures entities are traceable So that every rows in a table can be accessed via a unique ID.