Start Discovering Solved Questions and Your Course Assignments
TextBooks Included
Active Tutors
Asked Questions
Answered Questions
1consider a relation r with ve attributes abcde you are given the following dependencies a rarr b bc rarr e and ed rarr
briefy answer the following questions1 define the term functional dependency2 why are some functional dependencies
1consider the following collection of relations and dependencies as-sume that each relation is obtained through
suppose you are given a relation r with four attributes abcd for each of the following sets of fds assuming those are
consider a relation r that has three attributes abc it is decom-posed into relations r1 with attributes ab and r2 with
1jds are motivated by the fact that sometimes a relation that cannot be decomposed into two smaller relations in a
let r be decomposed into r1 r2 rn let f be a set of fds on rnbsp1 dene what it means for f to be preserved in the set
consider a relation r with ve attributes abcde1 for each of the following instances of r state whether it violates a
1describe a linear-time in the size of the set of fds where the size of each fd is the number of attributes involved
1give an algorithm for testing whether a relation scheme is in bcnf the algorithm should be polynomial in the size of
1prove that an mvd x rarrrarr y over a relation r can be expressed as the join dependency xy xr minus y 2let r be a
prove that the algorithm for decomposing a relation schema with a set of fds into a collection of bcnf relation schemas
consider the following bcnf schema for a portion of a simple cor-porate database type information is not relevant to
1the globetrotters club is organized into chapters the president of a chapter can never serve as the president of any
consider the following bcnf relational schema for a portion of a company database type information is not relevant to
consider the following bcnf relation which lists the ids types eg nuts or bolts and costs of various parts along with
1for each of the following queries identify one possible reason why an optimizer might not nd a good plan rewrite the
consider the following bcnf relations which describe departments in a company and employeesdeptdid dname location
consider two ways to compute the names of employees who earn more than 100000 and whose age is equal to their
briefy answer the following questions1 explain the intuition behind the two rules in the bell-lapadula model for
consider the following schemanbspsupplierssid integer sname string address string partspid integer pname string color
1write sql statements to create the corresponding relations to the er diagram you designed for exercise 28 if your
1explain the statement that relational algebra operators can be com-posed why is the ability to compose operators
briey answer the following questions based on this schemaempeid integer ename string age integer salary real workseid