Homework_3_Solution_revised

Homework_3_Solution_revised - Homework 3 Solution ISE 382...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Homework 3 Solution ISE 382 Spring 2006 A Assume that Marcia keeps a table of data about her customers. Consider just the following part of that table: CUSTOMER (Phone, FirstName, LastName) Explain the conditions under which each of the following are true: 1. Phone (FirstName, LastName) 2. (Phone, FirstName) LastName 3. (Phone, LastName) FirstName 4. (LastName, FirstName) Phone 5. Phone  LastName 6. Phone  FirstName 7. Phone  (FirstName, LastName) Is condition 7 the same as conditions 5 and 6? Why or why not? 1. Phone (FirstName, LastName) To answer function dependency questions remember this – If A -> B, then each value of A will be paired with one and only one value of B. A particular value of A may appear more than once in a relation, but if so, it is always paired with the same value of B. Note that the reverse is not necessarily true. If A - > B, then a value B may be paired with many values of A. Phone -> FirstName This is true if each phone is paired with only one first name. However, a firstname can have multiple phones Phone -> LastName
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 3

Homework_3_Solution_revised - Homework 3 Solution ISE 382...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online