Distributed Database Management Systems: Lecture 6

Distributed Database Management Systems: Lecture 6. The main topics covered in this chapter include: first three normal forms; boyce-code normal form; fourth normal form; P-J dependency; project-join dependency; integrity rules;...

Distributed Database Management System

Lecture 6

First Three Normal Forms

much interested in it Its more of a

historical perspective

XY where Y is not in X, either X is a

Boyce-Code Normal Form

X is the superkey

situation where a relation in in

3NF but not in BCNF, vice versa never happens

A relation R defined on attributes

a unique value of (Y,Z) pair and Z depends only on X then X

multidetermines Z, X > Z and

also X > Y

Fourth Normal Form

MVDs are also FDs

P-J Dependency

and Z then (X, Y, Z) constitute

project-join dependency for R

dependency is implied by the CKs

Integrity Rules

DB

since updates can lead to

inconsistencies