02 ICT118 SQL ERD Normal is at Ion Sem 2 2010

8/2/2019 02 ICT118 SQL ERD Normal is at Ion Sem 2 2010

1/13

22/07/2010

1

22 July, 2010 2. 1ICT118 Database and Information Management, Sem 2, 2010.Includes some Cengage material

Database and InformationDatabase and InformationDatabase and InformationDatabase and InformationRetrievalRetrievalRetrievalRetrieval

ICT118Lecture 2 Relational Theory

Entities and Normalisation


Database DesignDatabase DesignDatabase DesignDatabase Design

Storage of business information in a databaseStorage of business information in a databaseStorage of business information in a databaseStorage of business information in a databasemust be plannedmust be plannedmust be plannedmust be planned

Current database design is based on CoddsCurrent database design is based on CoddsCurrent database design is based on CoddsCurrent database design is based on Coddsrelational theoryrelational theoryrelational theoryrelational theory

Business needBusiness needBusiness needBusiness need entity identificationentity identificationentity identificationentity identification ERDERDERDERD

modellingmodellingmodellingmodelling normalisationnormalisationnormalisationnormalisation db designdb designdb designdb design


EntitiesEntitiesEntitiesEntitiesIdentifiable things of interest to the businessIdentifiable things of interest to the businessIdentifiable things of interest to the businessIdentifiable things of interest to the business

Entities do something or record somethingEntities do something or record somethingEntities do something or record somethingEntities do something or record something

Entities interact with other entities in theEntities interact with other entities in theEntities interact with other entities in theEntities interact with other entities in thebusinessbusinessbusinessbusiness interaction implies processinginteraction implies processinginteraction implies processinginteraction implies processing

Entities have attributesEntities have attributesEntities have attributesEntities have attributes


2/13

22/07/2010

2


EntityEntityEntityEntity----Relationship ModelRelationship ModelRelationship ModelRelationship Model

Used to depict the relationship thatUsed to depict the relationship thatUsed to depict the relationship thatUsed to depict the relationship thatexists among entitiesexists among entitiesexists among entitiesexists among entities

The following relationship types can beThe following relationship types can beThe following relationship types can beThe following relationship types can beincluded in an Eincluded in an Eincluded in an Eincluded in an E----R model:R model:R model:R model:

One-to-one

One-to-many

Many-to-many


EEEE----R Model Notation ExamplesR Model Notation ExamplesR Model Notation ExamplesR Model Notation Examples

One to one One to many

Many to many

EnrolmentStudent

Student Subject

Subject Examination


Notation conventionsNotation conventionsNotation conventionsNotation conventionsCardinality is the term which indicates theCardinality is the term which indicates theCardinality is the term which indicates theCardinality is the term which indicates the

number of required instances at each end ofnumber of required instances at each end ofnumber of required instances at each end ofnumber of required instances at each end ofa relationshipa relationshipa relationshipa relationship

One instance

Many instances


3/13

22/07/2010

3


Notation conventionsNotation conventionsNotation conventionsNotation conventionsOptionality indicates whether or not anOptionality indicates whether or not anOptionality indicates whether or not anOptionality indicates whether or not an

instance of an entity must exist in theinstance of an entity must exist in theinstance of an entity must exist in theinstance of an entity must exist in therelationship, or is optional. Numeric rangesrelationship, or is optional. Numeric rangesrelationship, or is optional. Numeric rangesrelationship, or is optional. Numeric rangescan be specifiedcan be specifiedcan be specifiedcan be specified

OptionalOptionalOptionalOptional

MandatoryMandatoryMandatoryMandatory

0..*


OneOneOneOne----totototo----One RelationshipOne RelationshipOne RelationshipOne Relationship

A record in one entity is related to only oneA record in one entity is related to only oneA record in one entity is related to only oneA record in one entity is related to only onerecord in the other entityrecord in the other entityrecord in the other entityrecord in the other entity

Example: Each aircraft passenger is allocatedExample: Each aircraft passenger is allocatedExample: Each aircraft passenger is allocatedExample: Each aircraft passenger is allocatedone seat, and each seat is allocated to justone seat, and each seat is allocated to justone seat, and each seat is allocated to justone seat, and each seat is allocated to justone passengerone passengerone passengerone passenger

PASSENGER SEAT


OneOneOneOne----totototo----Many RelationshipMany RelationshipMany RelationshipMany Relationship

Each record in one entity can be related to oneEach record in one entity can be related to oneEach record in one entity can be related to oneEach record in one entity can be related to oneor more records in the other entityor more records in the other entityor more records in the other entityor more records in the other entity

Example: A class has only one lecturer, butExample: A class has only one lecturer, butExample: A class has only one lecturer, butExample: A class has only one lecturer, buteach lecturer can teach many classeseach lecturer can teach many classeseach lecturer can teach many classeseach lecturer can teach many classes

LECTURER CLASS1..4


4/13

22/07/2010

4


ManyManyManyMany----totototo----Many RelationshipMany RelationshipMany RelationshipMany Relationship

Each record in an entity can be related toEach record in an entity can be related toEach record in an entity can be related toEach record in an entity can be related tomultiple occurrences in the other entitymultiple occurrences in the other entitymultiple occurrences in the other entitymultiple occurrences in the other entity

Example: A student can take many classes,Example: A student can take many classes,Example: A student can take many classes,Example: A student can take many classes,and each class is composed of manyand each class is composed of manyand each class is composed of manyand each class is composed of manystudentsstudentsstudentsstudents

STUDENT CLASS

10..25

1..5


EntityEntityEntityEntity----Relationship DiagramRelationship DiagramRelationship DiagramRelationship Diagram(ERD)(ERD)(ERD)(ERD)A diagrammatic representation of theA diagrammatic representation of theA diagrammatic representation of theA diagrammatic representation of the

relationships between all entities of interestrelationships between all entities of interestrelationships between all entities of interestrelationships between all entities of interestin a business situationin a business situationin a business situationin a business situation

Forms the basis for building a databaseForms the basis for building a databaseForms the basis for building a databaseForms the basis for building a database afterafterafterafter

the process of normalisationthe process of normalisationthe process of normalisationthe process of normalisation


JustLee Example EJustLee Example EJustLee Example EJustLee Example E----R ModelR ModelR ModelR Model

Figure 1-4 An E-R model for JustLee Books


5/13

22/07/2010

5


AttributesAttributesAttributesAttributesAn individual field that describes one aspect ofAn individual field that describes one aspect ofAn individual field that describes one aspect ofAn individual field that describes one aspect of

the entitythe entitythe entitythe entityA name Size12 100mm bolt

An identifier 0844255

A date 04-MAY-2010

A measurement 328

A reference 0844320

One or more attributes will uniquely identifyOne or more attributes will uniquely identifyOne or more attributes will uniquely identifyOne or more attributes will uniquely identifyeach instance of the entity (the key)each instance of the entity (the key)each instance of the entity (the key)each instance of the entity (the key)


AttributesAttributesAttributesAttributes

An entity wil l be composed of (described by) aAn entity will be composed of (described by) aAn entity wil l be composed of (described by) aAn entity will be composed of (described by) acollection of attributes which taken togethercollection of attributes which taken togethercollection of attributes which taken togethercollection of attributes which taken togetherrepresent that entityrepresent that entityrepresent that entityrepresent that entityName

Description

Size

ClassificationQuantity

The values of each attribute distinguish oneThe values of each attribute distinguish oneThe values of each attribute distinguish oneThe values of each attribute distinguish oneinstance of an entity from anotherinstance of an entity from anotherinstance of an entity from anotherinstance of an entity from another


Attribute sharingAttribute sharingAttribute sharingAttribute sharing

One particular attribute may beOne particular attribute may beOne particular attribute may beOne particular attribute may beassociated with several entitiesassociated with several entitiesassociated with several entitiesassociated with several entities

Product identifier in:Product identifier in:Product identifier in:Product identifier in:PRODUCT entity

ORDER entity

DELIVERY entity


6/13

22/07/2010

6


Functional DependencyFunctional DependencyFunctional DependencyFunctional Dependency

The concept that one thing depends on theThe concept that one thing depends on theThe concept that one thing depends on theThe concept that one thing depends on thevalue of another, (or that one thing isvalue of another, (or that one thing isvalue of another, (or that one thing isvalue of another, (or that one thing isdetermined by the value of another)determined by the value of another)determined by the value of another)determined by the value of another)

e.g. I need milk and it costs $1.50 per litre.e.g. I need milk and it costs $1.50 per litre.e.g. I need milk and it costs $1.50 per litre.e.g. I need milk and it costs $1.50 per litre.How much do I pay for milk? 2 litres = $3.00,How much do I pay for milk? 2 litres = $3.00,How much do I pay for milk? 2 litres = $3.00,How much do I pay for milk? 2 litres = $3.00,5 litres = $7.505 litres = $7.505 litres = $7.505 litres = $7.50

The amount I pay is determined by (dependentThe amount I pay is determined by (dependentThe amount I pay is determined by (dependentThe amount I pay is determined by (dependenton) the number of litreson) the number of litreson) the number of litreson) the number of litres

Quantity is the determinant of amount paidQuantity is the determinant of amount paidQuantity is the determinant of amount paidQuantity is the determinant of amount paid

Amount paid is functionally dependent onAmount paid is functionally dependent onAmount paid is functionally dependent onAmount paid is functionally dependent onquantityquantityquantityquantity


Determinants and RelationsDeterminants and RelationsDeterminants and RelationsDeterminants and Relations

Relational theory requires one determinant onlyRelational theory requires one determinant onlyRelational theory requires one determinant onlyRelational theory requires one determinant onlyfor a relation (table)for a relation (table)for a relation (table)for a relation (table)

A determinant is called a key, and there may beA determinant is called a key, and there may beA determinant is called a key, and there may beA determinant is called a key, and there may beseveral keys in the entities that we find. A keyseveral keys in the entities that we find. A keyseveral keys in the entities that we find. A keyseveral keys in the entities that we find. A keyor determinant is said toor determinant is said toor determinant is said toor determinant is said to IdentifyIdentifyIdentifyIdentify a relationa relationa relationa relation

The Normalisation process modifies our entitiesThe Normalisation process modifies our entitiesThe Normalisation process modifies our entitiesThe Normalisation process modifies our entitiesinto relations having a single determinantinto relations having a single determinantinto relations having a single determinantinto relations having a single determinant

One unOne unOne unOne un----normalised entity will probably producenormalised entity will probably producenormalised entity will probably producenormalised entity will probably produceseveral normalised relationsseveral normalised relationsseveral normalised relationsseveral normalised relations


Functional dependency and keysFunctional dependency and keysFunctional dependency and keysFunctional dependency and keys

Example from the text book.Example from the text book.Example from the text book.Example from the text book.

Where the value of an attribute can only haveWhere the value of an attribute can only haveWhere the value of an attribute can only haveWhere the value of an attribute can only haveone value for each value of its key attributeone value for each value of its key attributeone value for each value of its key attributeone value for each value of its key attribute

Publication date can only have one value forPublication date can only have one value forPublication date can only have one value forPublication date can only have one value foreach value of the key attribute ISBNeach value of the key attribute ISBNeach value of the key attribute ISBNeach value of the key attribute ISBN


7/13

22/07/2010

7


Notation conventionsNotation conventionsNotation conventionsNotation conventionsEntities are recorded as sequential lists ofEntities are recorded as sequential lists ofEntities are recorded as sequential lists ofEntities are recorded as sequential lists ofattributes within bracketsattributes within bracketsattributes within bracketsattributes within brackets

The primary identifying attribute(s) orThe primary identifying attribute(s) orThe primary identifying attribute(s) orThe primary identifying attribute(s) oridentifier, or key, or determinant is underlinedidentifier, or key, or determinant is underlinedidentifier, or key, or determinant is underlinedidentifier, or key, or determinant is underlined

Product (Product-code, Product-descr, Supplier-identifier, Quantity-on-hand, UOM, Reorder-qty,Cost, Retail, Product-family)


Notation conventionsNotation conventionsNotation conventionsNotation conventionsSome groups of attributes occur several timesSome groups of attributes occur several timesSome groups of attributes occur several timesSome groups of attributes occur several times

in any one instance of an entityin any one instance of an entityin any one instance of an entityin any one instance of an entity

Multiple subject results for one studentMultiple subject results for one studentMultiple subject results for one studentMultiple subject results for one studentStudent (Student-num, Course-code, Course-type,

Enrol-date, Finish-date, Graduation-date

(Subject-code, subject-name, semester, year,score, grade), term-address, home-address,Enrolment-type)

Follow this format convention for definingFollow this format convention for definingFollow this format convention for definingFollow this format convention for definingentitiesentitiesentitiesentities


Storing Entities in a databaseStoring Entities in a databaseStoring Entities in a databaseStoring Entities in a databaseEntities are stored in tables that conform toEntities are stored in tables that conform toEntities are stored in tables that conform toEntities are stored in tables that conform to

Codds relational theoryCodds relational theoryCodds relational theoryCodds relational theory

Table (or Relation) is a collection of rows ofTable (or Relation) is a collection of rows ofTable (or Relation) is a collection of rows ofTable (or Relation) is a collection of rows ofattributes that must have one value only in eachattributes that must have one value only in eachattributes that must have one value only in eachattributes that must have one value only in eachattributeattributeattributeattribute

Every row must have the same structureEvery row must have the same structureEvery row must have the same structureEvery row must have the same structure(sequence of attributes)(sequence of attributes)(sequence of attributes)(sequence of attributes)

Therefore a table resembles a regular matrixTherefore a table resembles a regular matrixTherefore a table resembles a regular matrixTherefore a table resembles a regular matrix

Normalisation produces correctly structuredNormalisation produces correctly structuredNormalisation produces correctly structuredNormalisation produces correctly structuredtablestablestablestables


8/13

22/07/2010

8


Entity NormalisationEntity NormalisationEntity NormalisationEntity NormalisationCreates entities where all attributes areCreates entities where all attributes areCreates entities where all attributes areCreates entities where all attributes are

functionally dependent on the key attribute(s)functionally dependent on the key attribute(s)functionally dependent on the key attribute(s)functionally dependent on the key attribute(s)

Eliminates the anomalies associated with unEliminates the anomalies associated with unEliminates the anomalies associated with unEliminates the anomalies associated with un----normalised entitiesnormalised entitiesnormalised entitiesnormalised entities

Minimises the number of entities in which aMinimises the number of entities in which aMinimises the number of entities in which aMinimises the number of entities in which agiven attribute must be storedgiven attribute must be storedgiven attribute must be storedgiven attribute must be stored

Normalisation is a multiNormalisation is a multiNormalisation is a multiNormalisation is a multi----step process that youstep process that youstep process that youstep process that youperform onperform onperform onperform on everyeveryeveryevery entityentityentityentity

Six normal forms (NF) exist. We focus on 4 only:Six normal forms (NF) exist. We focus on 4 only:Six normal forms (NF) exist. We focus on 4 only:Six normal forms (NF) exist. We focus on 4 only:

First NF, Second NF, Third NF, BoyceFirst NF, Second NF, Third NF, BoyceFirst NF, Second NF, Third NF, BoyceFirst NF, Second NF, Third NF, Boyce----Codd NFCodd NFCodd NFCodd NF


DefinitionsDefinitionsDefinitionsDefinitions [1][1][1][1]1NF: if, and only if, all underlying attribute1NF: if, and only if, all underlying attribute1NF: if, and only if, all underlying attribute1NF: if, and only if, all underlying attributevalues are atomic (i.e. cannot be meaningfullyvalues are atomic (i.e. cannot be meaningfullyvalues are atomic (i.e. cannot be meaningfullyvalues are atomic (i.e. cannot be meaningfullydecomposed)decomposed)decomposed)decomposed)

2NF: if, and only if, it is in 1NF and every non2NF: if, and only if, it is in 1NF and every non2NF: if, and only if, it is in 1NF and every non2NF: if, and only if, it is in 1NF and every non----key attribute is fully dependent on the primarykey attribute is fully dependent on the primarykey attribute is fully dependent on the primarykey attribute is fully dependent on the primarykeykeykeykey

3NF: if, and only if, it is in 2NF and every non3NF: if, and only if, it is in 2NF and every non3NF: if, and only if, it is in 2NF and every non3NF: if, and only if, it is in 2NF and every non----key attribute is nonkey attribute is nonkey attribute is nonkey attribute is non----transitively dependent ontransitively dependent ontransitively dependent ontransitively dependent onthe primary keythe primary keythe primary keythe primary key

[1] C.J. Date, An Introduction to Database Systems, 5th edn, Vol.1.Reading MA: Addison-Wesley, 1990, pp532-557.


DefinitionsDefinitionsDefinitionsDefinitions

BoyceBoyceBoyceBoyce----Codd Normal Form (BCNF) is a variantCodd Normal Form (BCNF) is a variantCodd Normal Form (BCNF) is a variantCodd Normal Form (BCNF) is a variantof 3NF for special cases:of 3NF for special cases:of 3NF for special cases:of 3NF for special cases:

1.1.1.1. when there are multiple candidate keyswhen there are multiple candidate keyswhen there are multiple candidate keyswhen there are multiple candidate keys

2.2.2.2. those candidate keys are composite keysthose candidate keys are composite keysthose candidate keys are composite keysthose candidate keys are composite keys

3.3.3.3. those candidate keys overlappedthose candidate keys overlappedthose candidate keys overlappedthose candidate keys overlapped

These cases are less common and we willThese cases are less common and we willThese cases are less common and we willThese cases are less common and we willrestrict our interest to the first three normalrestrict our interest to the first three normalrestrict our interest to the first three normalrestrict our interest to the first three normal

formsformsformsforms


9/13

22/07/2010

9


Normalisation ProcessNormalisation ProcessNormalisation ProcessNormalisation ProcessIdentify the attributes for each entity. TheseIdentify the attributes for each entity. TheseIdentify the attributes for each entity. TheseIdentify the attributes for each entity. These

are the unare the unare the unare the un----normalised entities (UNF)normalised entities (UNF)normalised entities (UNF)normalised entities (UNF)

Identify keys (uniquely identifying attributes)Identify keys (uniquely identifying attributes)Identify keys (uniquely identifying attributes)Identify keys (uniquely identifying attributes)

Identify then resolve nonIdentify then resolve nonIdentify then resolve nonIdentify then resolve non----atomic attributesatomic attributesatomic attributesatomic attributes(repeating groups) (1NF)(repeating groups) (1NF)(repeating groups) (1NF)(repeating groups) (1NF)

Identify then resolve partial dependenciesIdentify then resolve partial dependenciesIdentify then resolve partial dependenciesIdentify then resolve partial dependencies(2NF)(2NF)(2NF)(2NF)

Identify then resolve transitive dependenciesIdentify then resolve transitive dependenciesIdentify then resolve transitive dependenciesIdentify then resolve transitive dependencies(3NF)(3NF)(3NF)(3NF)


Normalisation ProcessNormalisation ProcessNormalisation ProcessNormalisation ProcessSelect an entitySelect an entitySelect an entitySelect an entity

Identify its attributes (ignore calculated fields)Identify its attributes (ignore calculated fields)Identify its attributes (ignore calculated fields)Identify its attributes (ignore calculated fields)

Do any of these recur as a repeating group?Do any of these recur as a repeating group?Do any of these recur as a repeating group?Do any of these recur as a repeating group?For any single instance of the entity are thererepetitions of groups of attributes?

Student:Identifier Does it Repeat? no

Names Does it Repeat? no

Address Does it Repeat? no

Subjects Does it Repeat? yes


Normalisation processNormalisation processNormalisation processNormalisation process

Document using the conventional formatDocument using the conventional formatDocument using the conventional formatDocument using the conventional format

Primary keys are identified (Primary keys are identified (Primary keys are identified (Primary keys are identified (underlinedunderlinedunderlinedunderlined))))

Repeating groups are removed into a new entity, alongRepeating groups are removed into a new entity, alongRepeating groups are removed into a new entity, alongRepeating groups are removed into a new entity, alongwith the primary keywith the primary keywith the primary keywith the primary key

Student (Student (Student (Student (StudentStudentStudentStudent----numnumnumnum, Course, Course, Course, Course----code, Coursecode, Coursecode, Coursecode, Course----type, Enroltype, Enroltype, Enroltype, Enrol----date, Finishdate, Finishdate, Finishdate, Finish----date, Graduatedate, Graduatedate, Graduatedate, Graduate----datedatedatedate((((SubjectSubjectSubjectSubject----codecodecodecode, subject, subject, subject, subject----name, semester,name, semester,name, semester,name, semester,year, score, grade), termyear, score, grade), termyear, score, grade), termyear, score, grade), term----address, homeaddress, homeaddress, homeaddress, home----address, Enrolmentaddress, Enrolmentaddress, Enrolmentaddress, Enrolment----type)type)type)type)

becomes:becomes:becomes:becomes:


10/13

22/07/2010

10


Normalisation ProcessNormalisation ProcessNormalisation ProcessNormalisation ProcessStudent (Student (Student (Student (StudentStudentStudentStudent----numnumnumnum, Course, Course, Course, Course----code, Coursecode, Coursecode, Coursecode, Course----

type, Enroltype, Enroltype, Enroltype, Enrol----date, Finishdate, Finishdate, Finishdate, Finish----date, Graduatedate, Graduatedate, Graduatedate, Graduate----date,date,date,date,TermTermTermTerm----address, Homeaddress, Homeaddress, Homeaddress, Home----address, Enrolmentaddress, Enrolmentaddress, Enrolmentaddress, Enrolment----type)type)type)type)

plusplusplusplus

Enrolment (Enrolment (Enrolment (Enrolment (StudentStudentStudentStudent----numnumnumnum,,,, SubjectSubjectSubjectSubject----codecodecodecode,,,,subjectsubjectsubjectsubject----name,name,name,name, semester, year, score, grade)semester, year, score, grade)semester, year, score, grade)semester, year, score, grade)

Both are in First Normal Form (1NF)Both are in First Normal Form (1NF)Both are in First Normal Form (1NF)Both are in First Normal Form (1NF)


Anomalies from unAnomalies from unAnomalies from unAnomalies from un----normalisednormalisednormalisednormaliseddatadatadatadataEnrolment (Enrolment (Enrolment (Enrolment (StudentStudentStudentStudent----numnumnumnum,,,, SubjectSubjectSubjectSubject----codecodecodecode,,,,

subjectsubjectsubjectsubject----name,name,name,name, semester, year, score, grade)semester, year, score, grade)semester, year, score, grade)semester, year, score, grade)

Delete anomalyDelete anomalyDelete anomalyDelete anomaly can lose student data when acan lose student data when acan lose student data when acan lose student data when asubject record is deletedsubject record is deletedsubject record is deletedsubject record is deleted

Insert anomalyInsert anomalyInsert anomalyInsert anomaly require information aboutrequire information aboutrequire information aboutrequire information about

multiple entities when wanting to add justmultiple entities when wanting to add justmultiple entities when wanting to add justmultiple entities when wanting to add justoneoneoneone

Update anomalyUpdate anomalyUpdate anomalyUpdate anomaly one column value changeone column value changeone column value changeone column value changerequires repetition of the change for everyrequires repetition of the change for everyrequires repetition of the change for everyrequires repetition of the change for everyrecordrecordrecordrecord


Normalisation ProcessNormalisation ProcessNormalisation ProcessNormalisation ProcessRetain every attribute from the UNF collectionRetain every attribute from the UNF collectionRetain every attribute from the UNF collectionRetain every attribute from the UNF collection

in the new 1NF collectionsin the new 1NF collectionsin the new 1NF collectionsin the new 1NF collections

Do not invent/create new attributesDo not invent/create new attributesDo not invent/create new attributesDo not invent/create new attributes

Remember to copy the key of the original unRemember to copy the key of the original unRemember to copy the key of the original unRemember to copy the key of the original un----normalised entity into the new entity formednormalised entity into the new entity formednormalised entity into the new entity formednormalised entity into the new entity formed

from the Repeating group of attributesfrom the Repeating group of attributesfrom the Repeating group of attributesfrom the Repeating group of attributes

If there is NO Repeating groupIf there is NO Repeating groupIf there is NO Repeating groupIf there is NO Repeating group then thethen thethen thethen theoriginal entity is already in First Normal Formoriginal entity is already in First Normal Formoriginal entity is already in First Normal Formoriginal entity is already in First Normal Form


11/13

22/07/2010

11


1NF to 2NF process1NF to 2NF process1NF to 2NF process1NF to 2NF process1NF entities with a single attribute as key are1NF entities with a single attribute as key are1NF entities with a single attribute as key are1NF entities with a single attribute as key are

already in 2NF !already in 2NF !already in 2NF !already in 2NF !

The process only applies to 1NF entities with aThe process only applies to 1NF entities with aThe process only applies to 1NF entities with aThe process only applies to 1NF entities with acompound key (2 or more attributes)compound key (2 or more attributes)compound key (2 or more attributes)compound key (2 or more attributes)



Check if any attributes are functionallyCheck if any attributes are functionallyCheck if any attributes are functionallyCheck if any attributes are functionallydependent on only part of the compound keydependent on only part of the compound keydependent on only part of the compound keydependent on only part of the compound key


SubjectSubjectSubjectSubject----name and semester are functionallyname and semester are functionallyname and semester are functionallyname and semester are functionallydependent only on Subjectdependent only on Subjectdependent only on Subjectdependent only on Subject----code because, ifcode because, ifcode because, ifcode because, ifonly Studentonly Studentonly Studentonly Student----num changed, subjectnum changed, subjectnum changed, subjectnum changed, subject----namenamenamenameand semester would NOT changeand semester would NOT changeand semester would NOT changeand semester would NOT change

1NF to 2NF Process1NF to 2NF Process1NF to 2NF Process1NF to 2NF Process



Becomes:Becomes:Becomes:Becomes:

Enrolment (Enrolment (Enrolment (Enrolment (StudentStudentStudentStudent----numnumnumnum,,,, SubjectSubjectSubjectSubject----codecodecodecode, year,, year,, year,, year,score, grade)score, grade)score, grade)score, grade)

PlusPlusPlusPlus

Subject (Subject (Subject (Subject (SubjectSubjectSubjectSubject----codecodecodecode, subject, subject, subject, subject----name,name,name,name,semester)semester)semester)semester)

All in second normal form (2NF)All in second normal form (2NF)All in second normal form (2NF)All in second normal form (2NF)

1NF to 2NF Process1NF to 2NF Process1NF to 2NF Process1NF to 2NF Process


12/13

22/07/2010

12


Current entity statusCurrent entity statusCurrent entity statusCurrent entity statusStudent (Student (Student (Student (StudentStudentStudentStudent----numnumnumnum, Course, Course, Course, Course----code, Coursecode, Coursecode, Coursecode, Course----

type, Enroltype, Enroltype, Enroltype, Enrol----date, Finishdate, Finishdate, Finishdate, Finish----date, Graduatedate, Graduatedate, Graduatedate, Graduate----date,date,date,date,TermTermTermTerm----address, Homeaddress, Homeaddress, Homeaddress, Home----address, Enrolmentaddress, Enrolmentaddress, Enrolmentaddress, Enrolment----type)type)type)type)



All in second normal form (2NF)All in second normal form (2NF)All in second normal form (2NF)All in second normal form (2NF)


2NF to 3NF Process2NF to 3NF Process2NF to 3NF Process2NF to 3NF ProcessCheck if any attributes are functionallyCheck if any attributes are functionallyCheck if any attributes are functionallyCheck if any attributes are functionally

dependent on any other nondependent on any other nondependent on any other nondependent on any other non----key attributeskey attributeskey attributeskey attributes

CourseCourseCourseCourse----type is transitively dependent ontype is transitively dependent ontype is transitively dependent ontype is transitively dependent onCourseCourseCourseCourse----code because, if Coursecode because, if Coursecode because, if Coursecode because, if Course----codecodecodecodechanges, so will Coursechanges, so will Coursechanges, so will Coursechanges, so will Course----typetypetypetype

Student (Student (Student (Student (StudentStudentStudentStudent----numnumnumnum, Course, Course, Course, Course----code, Coursecode, Coursecode, Coursecode, Course----type, Enroltype, Enroltype, Enroltype, Enrol----date, Finishdate, Finishdate, Finishdate, Finish----date, Graduatedate, Graduatedate, Graduatedate, Graduate----date,date,date,date,TermTermTermTerm----address, Homeaddress, Homeaddress, Homeaddress, Home----address, Enrolmentaddress, Enrolmentaddress, Enrolmentaddress, Enrolment----type)type)type)type)


2NF to 3NF Process2NF to 3NF Process2NF to 3NF Process2NF to 3NF ProcessStudent becomes:Student becomes:Student becomes:Student becomes:

Student (Student (Student (Student (StudentStudentStudentStudent----numnumnumnum, Course, Course, Course, Course----code, Enrolcode, Enrolcode, Enrolcode, Enrol----date, Finishdate, Finishdate, Finishdate, Finish----date, Graduatedate, Graduatedate, Graduatedate, Graduate----date, Termdate, Termdate, Termdate, Term----address, Homeaddress, Homeaddress, Homeaddress, Home----address, Enrolmentaddress, Enrolmentaddress, Enrolmentaddress, Enrolment----type)type)type)type)

Plus:Plus:Plus:Plus:

Course (Course (Course (Course (CourseCourseCourseCourse----codecodecodecode, Course, Course, Course, Course----type)type)type)type)

Both in third normal form (3NF) Note thatBoth in third normal form (3NF) Note thatBoth in third normal form (3NF) Note thatBoth in third normal form (3NF) Note thatCourseCourseCourseCourse----code remains in Student. Nevercode remains in Student. Nevercode remains in Student. Nevercode remains in Student. Neverdelete a key.delete a key.delete a key.delete a key.


13/13

22/07/2010

13


Final Result of NormalisationFinal Result of NormalisationFinal Result of NormalisationFinal Result of NormalisationStudent (Student (Student (Student (StudentStudentStudentStudent----numnumnumnum, Course, Course, Course, Course----code, Enrolcode, Enrolcode, Enrolcode, Enrol----

date, Finishdate, Finishdate, Finishdate, Finish----date, Graduatedate, Graduatedate, Graduatedate, Graduate----date, Termdate, Termdate, Termdate, Term----address, Homeaddress, Homeaddress, Homeaddress, Home----address, Enrolmentaddress, Enrolmentaddress, Enrolmentaddress, Enrolment----type)type)type)type)

Course (Course (Course (Course (CourseCourseCourseCourse----codecodecodecode, Course, Course, Course, Course----type)type)type)type)



All in third normal form (3NF)All in third normal form (3NF)All in third normal form (3NF)All in third normal form (3NF)

Date post:	06-Apr-2018
Category:	Documents
Upload:	danny-manno
View:	217 times
Download:	0 times

02 ICT118 SQL ERD Normal is at Ion Sem 2 2010

Documents