Normalisation. Why normalise? To improve (simplify) database design in order to. Avoid update problems Avoid redundancy Simplify update operations

Save this PDF as:
Size: px
Start display at page:

Download "Normalisation. Why normalise? To improve (simplify) database design in order to. Avoid update problems Avoid redundancy Simplify update operations"

Transcription

1 Normalisation Why normalise? To improve (simplify) database design in order to Avoid update problems Avoid redundancy Simplify update operations 1

2 Example ( the practical difference between a first normal form relation and an unnormalised table) EMPLOYEE-PROJECT EMP* EMP-NAME PROJECT E1 Smith CS 101 CS 203 EE 121 E2 Jones CS 202 CS 101 E3 Lee EE 410 2

3 Consider 2 transactions on EMPLOYEE-PROJECT T1: Insert the fact that Hanks works on project EE 202. T2: Insert the fact that Smith works on project EE

4 No difference between the two transactions with EMPLOYEE-PROJECT* EMPLOYEE-PROJECT* EMP# EMP-NAME PROJECT E1 Smith CS 101 E1 Smith CS 203 E1 Smith EE 121 E2 Jones CS 202 E2 Jones CS 101 E3 Lee EE 410 4

5 Normalisation theory allows us to detect such cases and shows how relations can be converted to more suitable forms. 5

6 Numerous normal forms have been defined: 1NF: first normal form 2NF: second normal form 3NF: third normal form BCNF: Boyce-Codd normal form o 4NF: fourth normal form o 5NF: fifth normal form 6

7 Each succeeding normal form improves on the previous one by specifying further constraints on the relations. 7

8 Definition: 1NF 1NF: A relation is in first normal form if and only if it contains atomic values only. 1NF relations can still have undesirable features. 8

9 Recall the S-P-SP Database Suppose we design the S-P-SP database differently: Instead of S(S#, SNAME, STATUS,CITY) SP(S#, P#, QTY) we have a single relation SSP (S#, SNAME, STATUS,CITY, P#, QTY). (leaving the P relation as it is). 9

10 S S# SNAME STATUS CITY S1 Smith 20 London S2 Jones 10 Paris S3 Blake 30 Paris S4 Clark 20 London S5 Adams 30 Athens 10

11 SP S# P# QTY S# P# QTY S1 P1 300 S4 P2 200 S1 P2 200 S4 P4 300 S1 P3 400 S4 P5 400 S1 P4 200 S1 P5 100 S1 P6 100 S2 P1 300 S2 P2 400 S3 P

12 An instance of the SSP S#SNAME STATUS CITY P# QTY S1Smith 20 London P1 300 S1Smith 20 London P2 200 S1Smith 20 London P3 400 S1Smith 20 London P4 200 S1Smith 20 London P5 100 S1Smith 20 London P6 100 S2Jones 10 Paris P1 300 S2Jones 10 Paris P2 400 S3Blake 30 Paris P2 200 S4Clark 20 London P2 200 S4Clark 20 London P4 300 S4Clark 20 London P

13 Do you see any problems with SSP? Redundancies e.g. every tuple for supplier S1 shows SNAME to be Smith, and CITY to be London. Update problems Suppose supplier S1 moves from London to Paris. 13

14 Compare With The Original Table S S# SNAME STATUS CITY S1 Smith 20 London S2 Jones 10 Paris S3 Blake 30 Paris S4 Clark 20 London S5 Adams 30 Athens 14

15 There are other problems associated with the design of the SSP relation which we will discuss later. To be able to identify all these problems and solutions in general, we have to know about functional dependencies. 15

16 Functional Dependencies Given a relation R, and X, Y subsets of the set of attributes of R, Y is functionally dependent on X if and only if each X-value in R has associated with it at most one Y-value in R. In other words, whenever two tuples of R agree on their X-value, they must also agree on their Y-value. The functional dependency of Y on X is expressed by X Y (read as "X functionally determines Y".) 16

17 Examples S.S# S.SNAME S.S# S.STATUS S.S# S.CITY or more succinctly S.S# S.(SNAME, STATUS, CITY) or S# SNAME, STATUS, CITY if the context of relation S is understood. 17

18 In relation SP: S#, P# QTY Note: Dependencies are a matter of the semantics of the data, not merely a matter of the data values that happen to appear in a relation at some particular time. 18

19 Exercise: Functional Dependencies Find the functional dependencies amongst the following attributes: Snumber Name TutorName TutorRoom# Degree LectureCourse (LC) LectureCourseGrade(LCG) LectureRoom# (LR) LectureTime (LT) LectureRoomCapacity (LRC) 19

20 Which of these hold? Snumber Name, TutorName, Degree TutorName TutorRoom# Snumber TutorRoom# Snumber LectureCourse LectureCourse LectureRoom# LectureRoom# LectureRoomCapacity LectureCourse LectureTime 20

21 Which of these hold? Snumber,Name TutorName LectureCourse,LectureTime LectureRoom# TutorName LectureCourse 21

22 Inference Axioms for functional dependencies Given a set of functional dependencies we can derive others using the following inference axioms. In these axioms: X, Y, Z, W denote sets of attributes, XY is a shorthand for X Y. 22

23 LHS = RHS If you know the items given on the LHS then you can infer the items on the RHS. 23

24 Axioms for functional dependencies A1:Reflexivity = X X A2:Augmentation X Y = XZ Y X Y = XZ YZ A3:Transitivity (X Y) (Y Z) = X Z The axioms A1-A3 are called Armstrong's axioms. 24

25 Example of Augmentation: Snumber TutorName Snumber, SName TutorName 25

26 Axioms cntd. A4: Additivity (X Y) (X Z) = X YZ A5: Projectivity X YZ = X Y X YZ = X Z A6:Pseudotransitivity (X Y) (YZ W) = XZ W A4-A6 can be derived from A1 - A3. 26

27 Exercise Derive A4 from A1 - A3. 27

28 X Y X Z??? X YZ given given 28

29 Some Useful Definitions A functional dependency of the form X Y is trivial iff Y X. (E.g AB A) Let F be a set of fds. The closure of F, denoted F +, is the set of all fds logically implied by F. Let X be a set of attributes. The set of all attributes functionally determined by X under a set F of fds is called the closure of X under F, and is denoted X + F. 29

30 Example: F: B C C D A E CE F Then B + F = {B, C, D} AB + F =??? 30

31 An Algorithm for computing result : = X; X + F while (changes to result) do for each fd B C in F do begin end; if B result then result:= result C 31

32 Example: Find AG + F where F is: F: A B CG I C D H C B H result = {A,G} result = {A,G,B,H} result = {A, G,B,H,C,I,D} result = {A,G,B,H,C,I,D} AG + F = {A,B,C,D,G,H,I} 32

33 The speed of the algorithm is dependent on the size of F. Also these functional dependencies are part of the integrity constraints of the data stored in the database. These constraints have to be checked when updating the database and maintained. So it can pay to reduce the size of F without changing its closure. 33

34 Integrity Constraints Name Degree Length of Degree Smith A. BEng 3 Smith B. MEng 4 Fran C. MSc 1 Jones D. MSc 1 Name Degree Degree Length of Degree Update: Change Length of Degree of Fran C. to 2. 34

35 Definition : equivalent sets of FDs Two sets of functional dependencies S1 and S2 are equivalent if and only if S1 + =S2 +, i.e. S1 implies all the fds in S2, and vice versa. Informally: S1 and S2 are equivalent if they contain exactly the same information. 35

36 Definition: Irreducible/Canonical Cover An irreducible cover for a set F of fds, denoted Fc, is a set of fds that satisfies the following four conditions: 1. F and Fc are equivalent. 2.The right-hand side of every dependency in Fc involves just one attribute. 36

37 3.The left-hand side of every dependency in Fc is irreducible, i.e. no attribute in any lefthand side can be discarded without changing the closure. 4. No fd in Fc can be discarded without changing the closure. 37

38 For each set of functional dependencies there exists at least one irreducible cover, but each set does not necessarily have a unique irreducible cover. 38

39 Example: Irreducible Cover F: A BC B C A B AB C AC D 39

40 A BC B C A B AB C AC D A B A C 40

41 First rewrite F as: A B A C B C A B AB C AC D This set is equivalent to F by additivity and projectivity. 41

42 A B A C B C A B A B AB C AC D 42

43 Delete the duplication of A B: A B A C B C AB C AC D 43

44 AB C can be deleted without changing the closure, because it is implied from A C by augmentation. A B A C B C AB C AC D 44

45 A B A C B C AC D 45

46 A B A C B C A C D 46

47 C can be deleted from AC D, because A D is implied from A C and AC D by augmentation and transitivity: A B A C B C A D 47

48 A B A C B C A D 48

49 Finally A C can be deleted because it is implied by A B and B C by transitivity: A B B C A D This final set is an irreducible cover for F. 49

50 Definitions: Candidate, Primary and Alternate Keys A set of attributes K of a relation R is a candidate key of R iff K satisfies the following two conditions: 1) K R This is a shorthand for saying that K functionally determines all attributes of R. 2) K' ( K' K and K' R) i.e. there is no proper subset of K that functionally determines all attributes of R. 50

51 Every relation has at least one candidate key. Some relations may have exactly one, but it is possible that some may have two or more. Historically, in the relational model, for any given relation, one of the candidate keys is chosen as the primary key, and then the remainder (if any) are called alternate keys. 51

52 Example Suppose in relation S, S# and SNAME both uniquely identify each supplier. Then S would have two candidate keys: S# and SNAME. We may choose S# as the primary key. Then SNAME becomes an alternate key. 52

53 The Entity Integrity Rule In the relational model, the primary key is constrained by the following integrity rule. Entity Integrity Rule: No attribute participating in the primary key of a relation is allowed to accept NULL values. ( NULL values represent unknown or non-existent values.) 53

54 Name Postcode Telephone Smith SW7 2BZ Jones SW5 5AT NULL Pitt NULL NULL = DO not know / Does not exist 54

55 Phew.. After all this work on FDs we will now use them to analyse the design of relations and improving the design through normalisation. 55

Functional Dependencies and Finding a Minimal Cover

Functional Dependencies and Finding a Minimal Cover Functional Dependencies and Finding a Minimal Cover Robert Soulé 1 Normalization An anomaly occurs in a database when you can update, insert, or delete data, and get undesired side-effects. These side

More information

Database Design and Normalization

Database Design and Normalization Database Design and Normalization CPS352: Database Systems Simon Miner Gordon College Last Revised: 9/27/12 Agenda Check-in Functional Dependencies (continued) Design Project E-R Diagram Presentations

More information

Database Design and Normalization

Database Design and Normalization Database Design and Normalization Chapter 10 (Week 11) EE562 Slides and Modified Slides from Database Management Systems, R. Ramakrishnan 1 Computing Closure F + Example: List all FDs with: - a single

More information

Relational Database Design

Relational Database Design Relational Database Design To generate a set of relation schemas that allows - to store information without unnecessary redundancy - to retrieve desired information easily Approach - design schema in appropriate

More information

Chapter 9: Normalization

Chapter 9: Normalization Chapter 9: Normalization Part 1: A Simple Example Part 2: Another Example & The Formal Stuff A Problem: Keeping Track of Invoices (cont d) Suppose we have some invoices that we may or may not want to refer

More information

Schema Refinement, Functional Dependencies, Normalization

Schema Refinement, Functional Dependencies, Normalization Schema Refinement, Functional Dependencies, Normalization MSCI 346: Database Systems Güneş Aluç, University of Waterloo Spring 2015 MSCI 346: Database Systems Chapter 19 1 / 42 Outline 1 Introduction Design

More information

Week 11: Normal Forms. Logical Database Design. Normal Forms and Normalization. Examples of Redundancy

Week 11: Normal Forms. Logical Database Design. Normal Forms and Normalization. Examples of Redundancy Week 11: Normal Forms Database Design Database Redundancies and Anomalies Functional Dependencies Entailment, Closure and Equivalence Lossless Decompositions The Third Normal Form (3NF) The Boyce-Codd

More information

Database Design and Normal Forms

Database Design and Normal Forms Database Design and Normal Forms Database Design coming up with a good schema is very important How do we characterize the goodness of a schema? If two or more alternative schemas are available how do

More information

Design of Relational Database Schemas

Design of Relational Database Schemas Design of Relational Database Schemas T. M. Murali October 27, November 1, 2010 Plan Till Thanksgiving What are the typical problems or anomalies in relational designs? Introduce the idea of decomposing

More information

Chapter 10. Functional Dependencies and Normalization for Relational Databases

Chapter 10. Functional Dependencies and Normalization for Relational Databases Chapter 10 Functional Dependencies and Normalization for Relational Databases Chapter Outline 1 Informal Design Guidelines for Relational Databases 1.1Semantics of the Relation Attributes 1.2 Redundant

More information

Database Management Systems. Redundancy and Other Problems. Redundancy

Database Management Systems. Redundancy and Other Problems. Redundancy Database Management Systems Winter 2004 CMPUT 391: Database Design Theory or Relational Normalization Theory Dr. Osmar R. Zaïane Lecture 2 Limitations of Relational Database Designs Provides a set of guidelines,

More information

Schema Design and Normal Forms Sid Name Level Rating Wage Hours

Schema Design and Normal Forms Sid Name Level Rating Wage Hours Entity-Relationship Diagram Schema Design and Sid Name Level Rating Wage Hours Database Management Systems, 2 nd Edition. R. Ramakrishnan and J. Gehrke 1 Database Management Systems, 2 nd Edition. R. Ramakrishnan

More information

Databases -Normalization III. (N Spadaccini 2010 and W Liu 2012) Databases - Normalization III 1 / 31

Databases -Normalization III. (N Spadaccini 2010 and W Liu 2012) Databases - Normalization III 1 / 31 Databases -Normalization III (N Spadaccini 2010 and W Liu 2012) Databases - Normalization III 1 / 31 This lecture This lecture describes 3rd normal form. (N Spadaccini 2010 and W Liu 2012) Databases -

More information

Schema Refinement and Normalization

Schema Refinement and Normalization Schema Refinement and Normalization Module 5, Lectures 3 and 4 Database Management Systems, R. Ramakrishnan 1 The Evils of Redundancy Redundancy is at the root of several problems associated with relational

More information

Theory of Relational Database Design and Normalization

Theory of Relational Database Design and Normalization Theory of Relational Database Design and Normalization (Based on Chapter 14 and some part of Chapter 15 in Fundamentals of Database Systems by Elmasri and Navathe, Ed. 3) 1 Informal Design Guidelines for

More information

Functional Dependencies and Normalization

Functional Dependencies and Normalization Functional Dependencies and Normalization 5DV119 Introduction to Database Management Umeå University Department of Computing Science Stephen J. Hegner hegner@cs.umu.se http://www.cs.umu.se/~hegner Functional

More information

CS143 Notes: Normalization Theory

CS143 Notes: Normalization Theory CS143 Notes: Normalization Theory Book Chapters (4th) Chapters 7.1-6, 7.8, 7.10 (5th) Chapters 7.1-6, 7.8 (6th) Chapters 8.1-6, 8.8 INTRODUCTION Main question How do we design good tables for a relational

More information

Normalisation to 3NF. Database Systems Lecture 11 Natasha Alechina

Normalisation to 3NF. Database Systems Lecture 11 Natasha Alechina Normalisation to 3NF Database Systems Lecture 11 Natasha Alechina In This Lecture Normalisation to 3NF Data redundancy Functional dependencies Normal forms First, Second, and Third Normal Forms For more

More information

Chapter 7: Relational Database Design

Chapter 7: Relational Database Design Chapter 7: Relational Database Design Database System Concepts, 5th Ed. See www.db book.com for conditions on re use Chapter 7: Relational Database Design Features of Good Relational Design Atomic Domains

More information

COSC344 Database Theory and Applications. Lecture 9 Normalisation. COSC344 Lecture 9 1

COSC344 Database Theory and Applications. Lecture 9 Normalisation. COSC344 Lecture 9 1 COSC344 Database Theory and Applications Lecture 9 Normalisation COSC344 Lecture 9 1 Overview Last Lecture Functional Dependencies This Lecture Normalisation Introduction 1NF 2NF 3NF BCNF Source: Section

More information

Relational Database Design: FD s & BCNF

Relational Database Design: FD s & BCNF CS145 Lecture Notes #5 Relational Database Design: FD s & BCNF Motivation Automatic translation from E/R or ODL may not produce the best relational design possible Sometimes database designers like to

More information

Chapter 15 Basics of Functional Dependencies and Normalization for Relational Databases

Chapter 15 Basics of Functional Dependencies and Normalization for Relational Databases Chapter 15 Basics of Functional Dependencies and Normalization for Relational Databases Copyright 2011 Pearson Education, Inc. Publishing as Pearson Addison-Wesley Chapter 15 Outline Informal Design Guidelines

More information

Limitations of E-R Designs. Relational Normalization Theory. Redundancy and Other Problems. Redundancy. Anomalies. Example

Limitations of E-R Designs. Relational Normalization Theory. Redundancy and Other Problems. Redundancy. Anomalies. Example Limitations of E-R Designs Relational Normalization Theory Chapter 6 Provides a set of guidelines, does not result in a unique database schema Does not provide a way of evaluating alternative schemas Normalization

More information

Functional Dependency and Normalization for Relational Databases

Functional Dependency and Normalization for Relational Databases Functional Dependency and Normalization for Relational Databases Introduction: Relational database design ultimately produces a set of relations. The implicit goals of the design activity are: information

More information

C# Cname Ccity.. P1# Date1 Qnt1 P2# Date2 P9# Date9 1 Codd London.. 1 21.01 20 2 23.01 2 Martin Paris.. 1 26.10 25 3 Deen London.. 2 29.

C# Cname Ccity.. P1# Date1 Qnt1 P2# Date2 P9# Date9 1 Codd London.. 1 21.01 20 2 23.01 2 Martin Paris.. 1 26.10 25 3 Deen London.. 2 29. 4. Normalisation 4.1 Introduction Suppose we are now given the task of designing and creating a database. How do we produce a good design? What relations should we have in the database? What attributes

More information

CS 377 Database Systems. Database Design Theory and Normalization. Li Xiong Department of Mathematics and Computer Science Emory University

CS 377 Database Systems. Database Design Theory and Normalization. Li Xiong Department of Mathematics and Computer Science Emory University CS 377 Database Systems Database Design Theory and Normalization Li Xiong Department of Mathematics and Computer Science Emory University 1 Relational database design So far Conceptual database design

More information

Normalization in Database Design

Normalization in Database Design in Database Design Marek Rychly mrychly@strathmore.edu Strathmore University, @ilabafrica & Brno University of Technology, Faculty of Information Technology Advanced Databases and Enterprise Systems 14

More information

normalisation Goals: Suppose we have a db scheme: is it good? define precise notions of the qualities of a relational database scheme

normalisation Goals: Suppose we have a db scheme: is it good? define precise notions of the qualities of a relational database scheme Goals: Suppose we have a db scheme: is it good? Suppose we have a db scheme derived from an ER diagram: is it good? define precise notions of the qualities of a relational database scheme define algorithms

More information

Why Is This Important? Schema Refinement and Normal Forms. The Evils of Redundancy. Functional Dependencies (FDs) Example (Contd.)

Why Is This Important? Schema Refinement and Normal Forms. The Evils of Redundancy. Functional Dependencies (FDs) Example (Contd.) Why Is This Important? Schema Refinement and Normal Forms Chapter 19 Many ways to model a given scenario in a database How do we find the best one? We will discuss objective criteria for evaluating database

More information

Database design theory, Part I

Database design theory, Part I Database design theory, Part I Functional dependencies Introduction As we saw in the last segment, designing a good database is a non trivial matter. The E/R model gives a useful rapid prototyping tool,

More information

Relational Normalization: Contents. Relational Database Design: Rationale. Relational Database Design. Motivation

Relational Normalization: Contents. Relational Database Design: Rationale. Relational Database Design. Motivation Relational Normalization: Contents Motivation Functional Dependencies First Normal Form Second Normal Form Third Normal Form Boyce-Codd Normal Form Decomposition Algorithms Multivalued Dependencies and

More information

Database Management System

Database Management System UNIT -6 Database Design Informal Design Guidelines for Relation Schemas; Functional Dependencies; Normal Forms Based on Primary Keys; General Definitions of Second and Third Normal Forms; Boyce-Codd Normal

More information

Theory behind Normalization & DB Design. Satisfiability: Does an FD hold? Lecture 12

Theory behind Normalization & DB Design. Satisfiability: Does an FD hold? Lecture 12 Theory behind Normalization & DB Design Lecture 12 Satisfiability: Does an FD hold? Satisfiability of FDs Given: FD X Y and relation R Output: Does R satisfy X Y? Algorithm: a.sort R on X b.do all the

More information

Chapter 10 Functional Dependencies and Normalization for Relational Databases

Chapter 10 Functional Dependencies and Normalization for Relational Databases Chapter 10 Functional Dependencies and Normalization for Relational Databases Copyright 2004 Pearson Education, Inc. Chapter Outline 1 Informal Design Guidelines for Relational Databases 1.1Semantics of

More information

Normalization. CIS 331: Introduction to Database Systems

Normalization. CIS 331: Introduction to Database Systems Normalization CIS 331: Introduction to Database Systems Normalization: Reminder Why do we need to normalize? To avoid redundancy (less storage space needed, and data is consistent) To avoid update/delete

More information

Chapter 5: FUNCTIONAL DEPENDENCIES AND NORMALIZATION FOR RELATIONAL DATABASES

Chapter 5: FUNCTIONAL DEPENDENCIES AND NORMALIZATION FOR RELATIONAL DATABASES 1 Chapter 5: FUNCTIONAL DEPENDENCIES AND NORMALIZATION FOR RELATIONAL DATABASES INFORMAL DESIGN GUIDELINES FOR RELATION SCHEMAS We discuss four informal measures of quality for relation schema design in

More information

Chapter 10. Functional Dependencies and Normalization for Relational Databases. Copyright 2007 Ramez Elmasri and Shamkant B.

Chapter 10. Functional Dependencies and Normalization for Relational Databases. Copyright 2007 Ramez Elmasri and Shamkant B. Chapter 10 Functional Dependencies and Normalization for Relational Databases Copyright 2007 Ramez Elmasri and Shamkant B. Navathe Chapter Outline 1 Informal Design Guidelines for Relational Databases

More information

Theory of Relational Database Design and Normalization

Theory of Relational Database Design and Normalization Theory of Relational Database Design and Normalization (Based on Chapter 14 and some part of Chapter 15 in Fundamentals of Database Systems by Elmasri and Navathe) 1 Informal Design Guidelines for Relational

More information

Chapter 8. Database Design II: Relational Normalization Theory

Chapter 8. Database Design II: Relational Normalization Theory Chapter 8 Database Design II: Relational Normalization Theory The E-R approach is a good way to start dealing with the complexity of modeling a real-world enterprise. However, it is only a set of guidelines

More information

Unit 3.1. Normalisation 1 - V2.0 1. Normalisation 1. Dr Gordon Russell, Copyright @ Napier University

Unit 3.1. Normalisation 1 - V2.0 1. Normalisation 1. Dr Gordon Russell, Copyright @ Napier University Normalisation 1 Unit 3.1 Normalisation 1 - V2.0 1 Normalisation Overview discuss entity integrity and referential integrity describe functional dependency normalise a relation to first formal form (1NF)

More information

Advanced Relational Database Design

Advanced Relational Database Design APPENDIX B Advanced Relational Database Design In this appendix we cover advanced topics in relational database design. We first present the theory of multivalued dependencies, including a set of sound

More information

Lecture Notes on Database Normalization

Lecture Notes on Database Normalization Lecture Notes on Database Normalization Chengkai Li Department of Computer Science and Engineering The University of Texas at Arlington April 15, 2012 I decided to write this document, because many students

More information

Normalisation 1. Chapter 4.1 V4.0. Copyright @ Napier University

Normalisation 1. Chapter 4.1 V4.0. Copyright @ Napier University Normalisation 1 Chapter 4.1 V4.0 Copyright @ Napier University Normalisation Overview discuss entity integrity and referential integrity describe functional dependency normalise a relation to first formal

More information

Relational Normalization Theory (supplemental material)

Relational Normalization Theory (supplemental material) Relational Normalization Theory (supplemental material) CSE 532, Theory of Database Systems Stony Brook University http://www.cs.stonybrook.edu/~cse532 2 Quiz 8 Consider a schema S with functional dependencies:

More information

Database Constraints and Design

Database Constraints and Design Database Constraints and Design We know that databases are often required to satisfy some integrity constraints. The most common ones are functional and inclusion dependencies. We ll study properties of

More information

Normalization of Database

Normalization of Database Normalization of Database UNIT-4 Database Normalisation is a technique of organizing the data in the database. Normalization is a systematic approach of decomposing tables to eliminate data redundancy

More information

Lecture 2 Normalization

Lecture 2 Normalization MIT 533 ระบบฐานข อม ล 2 Lecture 2 Normalization Walailuk University Lecture 2: Normalization 1 Objectives The purpose of normalization The identification of various types of update anomalies The concept

More information

Normalisation 6 TABLE OF CONTENTS LEARNING OUTCOMES

Normalisation 6 TABLE OF CONTENTS LEARNING OUTCOMES Topic Normalisation 6 LEARNING OUTCOMES When you have completed this Topic you should be able to: 1. Discuss importance of the normalisation in the database design. 2. Discuss the problems related to data

More information

LOGICAL DATABASE DESIGN

LOGICAL DATABASE DESIGN MODULE 8 LOGICAL DATABASE DESIGN OBJECTIVE QUESTIONS There are 4 alternative answers to each question. One of them is correct. Pick the correct answer. Do not guess. A key is given at the end of the module

More information

Relational Database Design Theory

Relational Database Design Theory Relational Database Design Theory Informal guidelines for good relational designs Functional dependencies Normal forms and normalization 1NF, 2NF, 3NF BCNF, 4NF, 5NF Inference rules on functional dependencies

More information

Introduction to Databases, Fall 2005 IT University of Copenhagen. Lecture 5: Normalization II; Database design case studies. September 26, 2005

Introduction to Databases, Fall 2005 IT University of Copenhagen. Lecture 5: Normalization II; Database design case studies. September 26, 2005 Introduction to Databases, Fall 2005 IT University of Copenhagen Lecture 5: Normalization II; Database design case studies September 26, 2005 Lecturer: Rasmus Pagh Today s lecture Normalization II: 3rd

More information

A. TRUE-FALSE: GROUP 2 PRACTICE EXAMPLES FOR THE REVIEW QUIZ:

A. TRUE-FALSE: GROUP 2 PRACTICE EXAMPLES FOR THE REVIEW QUIZ: GROUP 2 PRACTICE EXAMPLES FOR THE REVIEW QUIZ: Review Quiz will contain very similar question as below. Some questions may even be repeated. The order of the questions are random and are not in order of

More information

Determination of the normalization level of database schemas through equivalence classes of attributes

Determination of the normalization level of database schemas through equivalence classes of attributes Computer Science Journal of Moldova, vol.17, no.2(50), 2009 Determination of the normalization level of database schemas through equivalence classes of attributes Cotelea Vitalie Abstract In this paper,

More information

Limitations of DB Design Processes

Limitations of DB Design Processes Normalization CS 317/387 1 Limitations of DB Design Processes Provides a set of guidelines, does not result in a unique database schema Does not provide a way of evaluating alternative schemas Pitfalls:

More information

Normalisation in the Presence of Lists

Normalisation in the Presence of Lists 1 Normalisation in the Presence of Lists Sven Hartmann, Sebastian Link Information Science Research Centre, Massey University, Palmerston North, New Zealand 1. Motivation & Revision of the RDM 2. The Brouwerian

More information

An Algorithmic Approach to Database Normalization

An Algorithmic Approach to Database Normalization An Algorithmic Approach to Database Normalization M. Demba College of Computer Science and Information Aljouf University, Kingdom of Saudi Arabia bah.demba@ju.edu.sa ABSTRACT When an attempt is made to

More information

MCQs~Databases~Relational Model and Normalization http://en.wikipedia.org/wiki/database_normalization

MCQs~Databases~Relational Model and Normalization http://en.wikipedia.org/wiki/database_normalization http://en.wikipedia.org/wiki/database_normalization Database normalization is the process of organizing the fields and tables of a relational database to minimize redundancy. Normalization usually involves

More information

Functional Dependencies

Functional Dependencies BCNF and 3NF Functional Dependencies Functional dependencies: modeling constraints on attributes stud-id name address course-id session-id classroom instructor Functional dependencies should be obtained

More information

DATABASE NORMALIZATION

DATABASE NORMALIZATION DATABASE NORMALIZATION Normalization: process of efficiently organizing data in the DB. RELATIONS (attributes grouped together) Accurate representation of data, relationships and constraints. Goal: - Eliminate

More information

Theory I: Database Foundations

Theory I: Database Foundations Theory I: Database Foundations 19. 19. Theory I: Database Foundations 07.2012 1 Theory I: Database Foundations 20. Formal Design 20. 20: Formal Design We want to distinguish good from bad database design.

More information

Jordan University of Science & Technology Computer Science Department CS 728: Advanced Database Systems Midterm Exam First 2009/2010

Jordan University of Science & Technology Computer Science Department CS 728: Advanced Database Systems Midterm Exam First 2009/2010 Jordan University of Science & Technology Computer Science Department CS 728: Advanced Database Systems Midterm Exam First 2009/2010 Student Name: ID: Part 1: Multiple-Choice Questions (17 questions, 1

More information

Normalisation and Data Storage Devices

Normalisation and Data Storage Devices Unit 4 Normalisation and Data Storage Devices Structure 4.1 Introduction 4.2 Functional Dependency 4.3 Normalisation 4.3.1 Why do we Normalize a Relation? 4.3.2 Second Normal Form Relation 4.3.3 Third

More information

Overview of Database Management Systems

Overview of Database Management Systems Overview of Database Management Systems Goals: DBMS basic concepts Introduce underlying managerial issues Prepare for discussion of uses of DBMS, such as OLAP and database mining 1 Overview of Database

More information

Chapter 5: Logical Database Design and the Relational Model Part 2: Normalization. Introduction to Normalization. Normal Forms.

Chapter 5: Logical Database Design and the Relational Model Part 2: Normalization. Introduction to Normalization. Normal Forms. Chapter 5: Logical Database Design and the Relational Model Part 2: Normalization Modern Database Management 6 th Edition Jeffrey A. Hoffer, Mary B. Prescott, Fred R. McFadden Robert C. Nickerson ISYS

More information

Normalization. Normalization. Normalization. Data Redundancy

Normalization. Normalization. Normalization. Data Redundancy Normalization Normalization o Main objective in developing a logical data model for relational database systems is to create an accurate representation of the data, its relationships, and constraints.

More information

Normalization for Relational DBs

Normalization for Relational DBs Chapter 7 Functional Dependencies & Normalization for Relational DBs Truong Quynh Chi tqchi@cse.hcmut.edu.vn Spring- 2013 Top-Down Database Design Mini-world Requirements E1 R Relation schemas Conceptual

More information

DATABASE DESIGN: NORMALIZATION NOTE & EXERCISES (Up to 3NF)

DATABASE DESIGN: NORMALIZATION NOTE & EXERCISES (Up to 3NF) DATABASE DESIGN: NORMALIZATION NOTE & EXERCISES (Up to 3NF) Tables that contain redundant data can suffer from update anomalies, which can introduce inconsistencies into a database. The rules associated

More information

Objectives of Database Design Functional Dependencies 1st Normal Form Decomposition Boyce-Codd Normal Form 3rd Normal Form Multivalue Dependencies

Objectives of Database Design Functional Dependencies 1st Normal Form Decomposition Boyce-Codd Normal Form 3rd Normal Form Multivalue Dependencies Objectives of Database Design Functional Dependencies 1st Normal Form Decomposition Boyce-Codd Normal Form 3rd Normal Form Multivalue Dependencies 4th Normal Form General view over the design process 1

More information

Part 6. Normalization

Part 6. Normalization Part 6 Normalization Normal Form Overview Universe of All Data Relations (normalized / unnormalized 1st Normal Form 2nd Normal Form 3rd Normal Form Boyce-Codd Normal Form (BCNF) 4th Normal Form 5th Normal

More information

Normalization. Functional Dependence. Normalization. Normalization. GIS Applications. Spring 2011

Normalization. Functional Dependence. Normalization. Normalization. GIS Applications. Spring 2011 Normalization Normalization Normalization is a foundation for relational database design Systematic approach to efficiently organize data in a database GIS Applications Spring 2011 Objectives Minimize

More information

Introduction to Database Systems. Normalization

Introduction to Database Systems. Normalization Introduction to Database Systems Normalization Werner Nutt 1 Normalization 1. Anomalies 1. Anomalies 2. Boyce-Codd Normal Form 3. 3 rd Normal Form 2 Anomalies The goal of relational schema design is to

More information

SQL DDL. DBS Database Systems Designing Relational Databases. Inclusion Constraints. Key Constraints

SQL DDL. DBS Database Systems Designing Relational Databases. Inclusion Constraints. Key Constraints DBS Database Systems Designing Relational Databases Peter Buneman 12 October 2010 SQL DDL In its simplest use, SQL s Data Definition Language (DDL) provides a name and a type for each column of a table.

More information

Topic 5.1: Database Tables and Normalization

Topic 5.1: Database Tables and Normalization Topic 5.1: Database Tables and Normalization What is Normalization? Normalization is a process for evaluating and correcting table structures to minimize data redundancies, thereby helping to eliminate

More information

Introduction to Database Systems. Chapter 4 Normal Forms in the Relational Model. Chapter 4 Normal Forms

Introduction to Database Systems. Chapter 4 Normal Forms in the Relational Model. Chapter 4 Normal Forms Introduction to Database Systems Winter term 2013/2014 Melanie Herschel melanie.herschel@lri.fr Université Paris Sud, LRI 1 Chapter 4 Normal Forms in the Relational Model After completing this chapter,

More information

Module 5: Normalization of database tables

Module 5: Normalization of database tables Module 5: Normalization of database tables Normalization is a process for evaluating and correcting table structures to minimize data redundancies, thereby reducing the likelihood of data anomalies. The

More information

6.830 Lecture 3 9.16.2015 PS1 Due Next Time (Tuesday!) Lab 1 Out today start early! Relational Model Continued, and Schema Design and Normalization

6.830 Lecture 3 9.16.2015 PS1 Due Next Time (Tuesday!) Lab 1 Out today start early! Relational Model Continued, and Schema Design and Normalization 6.830 Lecture 3 9.16.2015 PS1 Due Next Time (Tuesday!) Lab 1 Out today start early! Relational Model Continued, and Schema Design and Normalization Animals(name,age,species,cageno,keptby,feedtime) Keeper(id,name)

More information

Lecture 6. SQL, Logical DB Design

Lecture 6. SQL, Logical DB Design Lecture 6 SQL, Logical DB Design Relational Query Languages A major strength of the relational model: supports simple, powerful querying of data. Queries can be written intuitively, and the DBMS is responsible

More information

RELATIONAL DATABASE DESIGN

RELATIONAL DATABASE DESIGN RELATIONAL DATABASE DESIGN g Good database design - Avoiding anomalies g Functional Dependencies g Normalization & Decomposition Using Functional Dependencies g 1NF - Atomic Domains and First Normal Form

More information

Database Design. Marta Jakubowska-Sobczak IT/ADC based on slides prepared by Paula Figueiredo, IT/DB

Database Design. Marta Jakubowska-Sobczak IT/ADC based on slides prepared by Paula Figueiredo, IT/DB Marta Jakubowska-Sobczak IT/ADC based on slides prepared by Paula Figueiredo, IT/DB Outline Database concepts Conceptual Design Logical Design Communicating with the RDBMS 2 Some concepts Database: an

More information

Introduction to Microsoft Jet SQL

Introduction to Microsoft Jet SQL Introduction to Microsoft Jet SQL Microsoft Jet SQL is a relational database language based on the SQL 1989 standard of the American Standards Institute (ANSI). Microsoft Jet SQL contains two kinds of

More information

Design Theory for Relational Databases: Functional Dependencies and Normalization

Design Theory for Relational Databases: Functional Dependencies and Normalization Design Theory for Relational Databases: Functional Dependencies and Normalization Juliana Freire Some slides adapted from L. Delcambre, R. Ramakrishnan, G. Lindstrom, J. Ullman and Silberschatz, Korth

More information

Normalization of database model. Pazmany Peter Catholic University 2005 Zoltan Fodroczi

Normalization of database model. Pazmany Peter Catholic University 2005 Zoltan Fodroczi Normalization of database model Pazmany Peter Catholic University 2005 Zoltan Fodroczi Closure of an attribute set Given a set of attributes α define the closure of attribute set α under F (denoted as

More information

A Web-Based Environment for Learning Normalization of Relational Database Schemata

A Web-Based Environment for Learning Normalization of Relational Database Schemata A Web-Based Environment for Learning Normalization of Relational Database Schemata Nikolay Georgiev September 2008 Master s Thesis in Computing Science, 30 ECTS credits Supervisor at CS-UmU: Stephen J.

More information

3. Relational Model and Relational Algebra

3. Relational Model and Relational Algebra ECS-165A WQ 11 36 3. Relational Model and Relational Algebra Contents Fundamental Concepts of the Relational Model Integrity Constraints Translation ER schema Relational Database Schema Relational Algebra

More information

BCA. Database Management System

BCA. Database Management System BCA IV Sem Database Management System Multiple choice questions 1. A Database Management System (DBMS) is A. Collection of interrelated data B. Collection of programs to access data C. Collection of data

More information

DATABASE SYSTEMS. Chapter 7 Normalisation

DATABASE SYSTEMS. Chapter 7 Normalisation DATABASE SYSTEMS DESIGN IMPLEMENTATION AND MANAGEMENT INTERNATIONAL EDITION ROB CORONEL CROCKETT Chapter 7 Normalisation 1 (Rob, Coronel & Crockett 978184480731) In this chapter, you will learn: What normalization

More information

2. Basic Relational Data Model

2. Basic Relational Data Model 2. Basic Relational Data Model 2.1 Introduction Basic concepts of information models, their realisation in databases comprising data objects and object relationships, and their management by DBMS s that

More information

CSCI-GA.2433-001 Database Systems Lecture 7: Schema Refinement and Normalization

CSCI-GA.2433-001 Database Systems Lecture 7: Schema Refinement and Normalization CSCI-GA.2433-001 Database Systems Lecture 7: Schema Refinement and Normalization Mohamed Zahran (aka Z) mzahran@cs.nyu.edu http://www.mzahran.com View 1 View 2 View 3 Conceptual Schema At that point we

More information

Denormalisation (But not hacking it)

Denormalisation (But not hacking it) Denormalisation (But not hacking it) Denormalisation: Why, What, and How? Rodgers Oracle Performance Tuning Corrigan/Gurry Ch. 5, p69 Stephen Mc Kearney, 2001. 1 Overview Purpose of normalisation Methods

More information

Teaching Database Modeling and Design: Areas of Confusion and Helpful Hints

Teaching Database Modeling and Design: Areas of Confusion and Helpful Hints Journal of Information Technology Education Volume 6, 2007 Teaching Database Modeling and Design: Areas of Confusion and Helpful Hints George C. Philip, Ph. D. College of Business, The University of Wisconsin

More information

The Relational Model. Why Study the Relational Model?

The Relational Model. Why Study the Relational Model? The Relational Model Chapter 3 Instructor: Vladimir Zadorozhny vladimir@sis.pitt.edu Information Science Program School of Information Sciences, University of Pittsburgh 1 Why Study the Relational Model?

More information

The Relational Model. Why Study the Relational Model? Relational Database: Definitions

The Relational Model. Why Study the Relational Model? Relational Database: Definitions The Relational Model Database Management Systems, R. Ramakrishnan and J. Gehrke 1 Why Study the Relational Model? Most widely used model. Vendors: IBM, Microsoft, Oracle, Sybase, etc. Legacy systems in

More information

Answer Key. UNIVERSITY OF CALIFORNIA College of Engineering Department of EECS, Computer Science Division

Answer Key. UNIVERSITY OF CALIFORNIA College of Engineering Department of EECS, Computer Science Division Answer Key UNIVERSITY OF CALIFORNIA College of Engineering Department of EECS, Computer Science Division CS186 Fall 2003 Eben Haber Midterm Midterm Exam: Introduction to Database Systems This exam has

More information

SQL DATA DEFINITION: KEY CONSTRAINTS. CS121: Introduction to Relational Database Systems Fall 2015 Lecture 7

SQL DATA DEFINITION: KEY CONSTRAINTS. CS121: Introduction to Relational Database Systems Fall 2015 Lecture 7 SQL DATA DEFINITION: KEY CONSTRAINTS CS121: Introduction to Relational Database Systems Fall 2015 Lecture 7 Data Definition 2 Covered most of SQL data manipulation operations Continue exploration of SQL

More information

The Relational Model. Ramakrishnan&Gehrke, Chapter 3 CS4320 1

The Relational Model. Ramakrishnan&Gehrke, Chapter 3 CS4320 1 The Relational Model Ramakrishnan&Gehrke, Chapter 3 CS4320 1 Why Study the Relational Model? Most widely used model. Vendors: IBM, Informix, Microsoft, Oracle, Sybase, etc. Legacy systems in older models

More information

Effective Pruning for the Discovery of Conditional Functional Dependencies

Effective Pruning for the Discovery of Conditional Functional Dependencies Effective Pruning for the Discovery of Conditional Functional Dependencies Jiuyong Li 1, Jiuxue Liu 1, Hannu Toivonen 2, Jianming Yong 3 1 School of Computer and Information Science, University of South

More information

Normalization in OODB Design

Normalization in OODB Design Normalization in OODB Design Byung S. Lee Graduate Programs in Software University of St. Thomas St. Paul, Minnesota bslee@stthomas.edu Abstract When we design an object-oriented database schema, we need

More information

Introduction Decomposition Simple Synthesis Bernstein Synthesis and Beyond. 6. Normalization. Stéphane Bressan. January 28, 2015

Introduction Decomposition Simple Synthesis Bernstein Synthesis and Beyond. 6. Normalization. Stéphane Bressan. January 28, 2015 6. Normalization Stéphane Bressan January 28, 2015 1 / 42 This lecture is based on material by Professor Ling Tok Wang. CS 4221: Database Design The Relational Model Ling Tok Wang National University of

More information

Boyce-Codd Normal Form

Boyce-Codd Normal Form 4NF Boyce-Codd Normal Form A relation schema R is in BCNF if for all functional dependencies in F + of the form α β at least one of the following holds α β is trivial (i.e., β α) α is a superkey for R

More information

Graham Kemp (telephone 772 54 11, room 6475 EDIT) The examiner will visit the exam room at 15:00 and 17:00.

Graham Kemp (telephone 772 54 11, room 6475 EDIT) The examiner will visit the exam room at 15:00 and 17:00. CHALMERS UNIVERSITY OF TECHNOLOGY Department of Computer Science and Engineering Examination in Databases, TDA357/DIT620 Tuesday 17 December 2013, 14:00-18:00 Examiner: Results: Exam review: Grades: Graham

More information