91Ó°ÊÓ

Define Boyce-Codd normal form. How does it differ from 3NF? Why is it consid. ered a stronger form of \(3 \mathrm{NF}\) ?

Suppose that we have the following requirements for a university database that is used to keep track of students' transcripts: a. The university keeps track of each student's name (SNAME), student number (SNUM), social security number (SSN), current address (SCADDR) and phone \((\mathrm{SCPHONE}),\) permanent address \((\mathrm{SPADDR})\) and phone \((\mathrm{SPPHONE}),\) birth date \((\mathrm{BDATE})\) \(\operatorname{sex}(\operatorname{sex}), \text { class (cLass) (freshman, sophomore, } \ldots, \text { graduate }),\) major depart ment (MAJORCODE), minor department (MINORCODE) (if any), and degree program \(\left(p_{R O C}\right)(B, A,, B, S, \ldots, P H, D,) .\) Both sss \(N\) and student number have unique val. ues for each student. b. Each department is described by a name (DNAME), department code (DCOOE), office number (DOFFICE), office phone (DPHONE), and college (DCOLLECE). Both name and code have unique values for each department. c. Each course has a course name (cNAME), description (cDESC), course number (CNUM), number of semester hours (cREDIT), level (LEVEL), and offering depart. ment (coept). The course number is unique for each course. d. Each section has an instructor (INAME), semester (SEMESTER), year (YEAR), course (seccourse), and section number (secwum). The section number distinguishes different sections of the same course that are taught during the same semester/ year; its values are \(1,2,3, \ldots,\) up to the total number of sections taught during each semester. e. \(A\) grade record refers to a student \((\operatorname{ss} N),\) a particular section, and a grade \((\mathrm{CRADE})\) Design a relational database schema for this database application. First show all the functional dependencies that should hold among the attributes. Then design relation schemas for the database that are each in \(3 \mathrm{NF}\) or BCNF. Specify the key attributes of each relation. Note any unspecified requirements, and make appropriate assumptions to render the specification complete.

Consider the following two sets of functional dependencies: \(F=\\{A \rightarrow C, A C \rightarrow\) \(D, E \rightarrow A D, E \rightarrow H\\}\) and \(G=\\{A \rightarrow C D, E \rightarrow A H\\} .\) Check whether they are equivalent.

Prove that any relation schema with two attributes is in BCNF.

Consider the universal relation \(R=\\{A, B, C, D, E, F, G, H, I, J\\}\) and the set of func- \\[ \text { tional dependencies } F=\\{\\{A, B\\} \rightarrow\\{C\\},\\{A\\} \rightarrow\\{D, E\\},\\{B\\} \rightarrow\\{F\\},\\{F\\} \rightarrow\\{G, H\\},\\{D\\} \rightarrow \\] \(\\{I, J\\} .\) What is the key for \(R ?\) Decompose \(R\) into \(2 \mathrm{NF}\) and then \(3 \mathrm{NF}\) relations.

Consider a relation \(R(A, B, C, D, E)\) with the following dependencies: \\[ A B \rightarrow C, C D \rightarrow E, D E \rightarrow B \\] Is \(A B\) a candidate key of this relation? If not, is \(A B D ?\) Explain your answer.

Consider the following relation for published books: BOOK (Book_title, Authorname, Book_type, Listprice, Author_affil, Publisher) Author_affil refers to the affliation of author. Suppose the following dependencies exist: Book_title \(\rightarrow\) Publisher, Book_type Book_type \(\rightarrow\) Listprice Authorname \(\rightarrow\) Author-affil a. What normal form is the relation in? Explain your answer. b. Apply normalization until you cannot decompose the relations further. State the reasons behind each decomposition.