Entity-Relationship Model€¦ · saklviTüal½y ebolR)ay Entity-Relationship Model CMBUk TI 4...

saklviTüal½y ebolR)ay Entity-Relationship Model

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Entity-Relationship (E-R) model KWCa high-level conceptual data model

EdlRtUv)anbegáIteLIgeday Chen kñúgqñaM 1976 edIm,ICYysMrYlkarksag database. Conceptual data model KWCasMnMuén concepts EdlBN’naGMBIrcnasm<½n§ (structure)

én database nig retrieval and update transaction elI database. eKalbMNg CacMbgkñúgkarksag high-level data model KWedIm,IpÁt;pÁg;karyl;eXIjeTAelI Tinñn½yrbs; user niglak;bM)aMgcMnucbec©keTsBak;B½n§dl;karksag database (The main purpose for developing a high-level data model is to support a user’s perception of the data and to conceal the more technical aspects associated with database design.) elIsBIenHeTot conceptual data model KWminGaRs½yeTAnwg DBMS nig Hardware platform EdleRbIR)as;sMrab;begáIt database eT. 1. The Concepts of the Entity-Relationship Model Basic concepts én entity-relationship model rYmman entity types,

relationship types, and attributes.

1. 1. Entity Types (Entity Sets) Entity is a person, place, object, or event in the user environment about

which the organization wishes to maintain data. Entity KWCamnusS/ TIkEnøg/ vtßú rWRBwtþikarN_kñúgmCÄdæanGñkeRbIR)as;Edl

organization cg;eFVIkarEfTaMTinñn½y. ]TahrN_mYycMnYneTAelI entities:

Person : EMPLOYEE, STUDENT, PATIENT Place : STORE, WAREHOUSE, STATE Object : MACHINE, BUILDING, AUTOMOBILE Event : SALE, REGISTRATION, RENEWAL

eroberogedaysa®sþacarü kaMg cnßa TMB½rTI 49


Entity type (Entity set) is a collection of entities that share common properties or characteristics. Entity type KWCakarRbmUlpþMú entities EdleRbIR)as;lkçN³rYm. RKb; entity type

kñúg entity-relationship diagram EtgEtmaneQμaHEdlsßitkñúgctuekaNEkgmYy (rectangle) ehIyeQ μaHenaHeRcInEtCaGkSrFMTaMgGs; ehIymanlkçN³ singular.

(rUb 4.1) Entity instance or Entity occurrence is a single occurrence of an entity type.

EMPLOYEE

Entity instance rW Entity occurrence KWsMedAelIkarelceLIg rWbgðajEtmþgkñúg entity type. ]TahrN_³

Entity type: EMPLOYEE Attributes: EMPLOYEE NUMBER CHAR(10) NAME CHAR(25) ADDRESS CHAR(30) ZIP CHAR(9) DATE HIRED DATE BIRTHDATE DATE Two Instances of EMPLOYEE:

642-17-8360 534-10-1971 Michelle Brady David Johnson 100 Pacific Avenue 450 Redwood Drive San Francisco Redwood City 98173 97142

03-21-1992 08-16-1994 06-19-1968 09-04-1975 (rUb 4.2)

Strong entity type (Strong entity set) is an entity type that exists independently of other entity type. Strong entity type KWCa entity type EdlekItmaneLIgedayminBwgBak;elI entity type d¾éTeTot. ]TahrN_³ STUDENT, EMPLOYEE, AUTOMOBILE nig COURSE suT§EtCa strong entity type. Weak entity type (Weak entity set) is an entity type whose existence depends on some other entity type.



Weak entity type KWCa entity type EdlekItmaneLIgedayBwgBak;elI entity

type epSgeTot. Weak entity type KμanGtßn½yRKb;RKan;eTxagvis½yCMnYjenAkñúg ER

diagram RbsinebIKμankarcUlrYmBI entity type EdlvaBwgBak;eT. Entity type

EdlvaBwgBak; eKehAfa identifying owner rW owner. Weak entity type Kμan identifier ekIteLIgeday attributes rbs;vaeT ehIyCaTUeTAkñúg ER diagram, weak

entity type man attributes bMerIkarCa partial key. Full key én weak entity type

ekItBIkarcUlpSMKñarvag partial key nig key én owner. Weak entity type

bgðajedayrUb double rectangles. ]TahrN_³ DEPEDENT KWCa weak entity type

eRBaHvak¾ekIteLIg)anGaRs½yelI owner entity EdltP¢ab;CamYyva.

(rUb 4.3)

1. 2. Attributes Attribute is a property of an entity or a relationship type. Attribute KWCalkçN³ rWCabMENkB½t’manén entity rW relationship. CagenHeTA eTot ral; entity instance TaMgGs;én entity type suT§Etman attributes dUcKñaTaMgGs;. Attribute én entity pÞúktMélEdlBN’naGMBI entity nImYy² ehIytMélenaHbgðajBIcMnucd¾ sMxan;énTinñn½yrkSaTukkñúg database.

Has EMPLOYEE

Employee_Name

Employee_ID Dependent_Name BirthDate

Partial key

DEPENDENT

Sex

Weak entity type Owner

Identifying relationship



]TahrN_³ BRANCH entity man attributes dUcCa branch number

(Branch_No), address (Address), phone number (Telephone) nig fax number

(Fax_No). Attribute domain is a set of values that may be assigned to an attribute. Attribute domain KWCasMnMutMélEdl)ankMnt;eTAelI attribute. ral; attributes

TaMgGs;suT§EtmantMélEdlGnuBaØatieGaybBa©Úl rW domain rbs;eKpÞal; ehIyCagenHeTA eTotkarbBa©ÚlTinñn½yeTAkan; attribute én entity type suT§EtTajecjBI domain rbs;va TaMgGs;. ]TahrN_³ Domain én attribute Sex manRbePTTinñn½yCatYGkSr (string or

text) ehIybBa©Úl)anEt 1 tYGkSrKt;KW M rW F. Data Type : Text Field Size : 1 Values : M or F Domain én attribute Score manRbePTTinñn½yCaelxmanek,ós (float or

single) ehIyGacbBa©ÚltMélcab;BI 0 eTAkan; 100. Data Type : Number Field Size : Single Values : 1 to 100 Domain én attribute Employee_Name manRbePTTinñn½yCaGkSr (string or

text) ehIybBa©Úl)anEt 50 tYGkSrKt;. Data Type : Text Field Size : 50 Values : Unlimited Attributes mYycMnYnGaceRbIR)as; domain rYm (Attributes may share a

domain). ]TahrN_³ Address attributes én Staff nig Owner entities eRbIR)as; domain rYm. eyIgeFVIkarEbkEckcMNat;fñak; attribute Ca³ simple or composite; single-valued or multi-valued; or derived.

A. Simple Attribute Simple (Atomic) Attribute is an attribute that cannot be broken down

into smaller components. Simple (Atomic) attribute KWCa attribute EdlminGacbMEbkteTAeTot)an.



]TahrN_ ³ Attribute Sex, Employee_ID, Weight, BirthDate Ca Simple

attribute BIeRBaHvaminGaceFVIkarbMEbkteTAeTot)an. B. Composite Attribute Composite Attribute is an attribute that can be broken down into

component parts. Composite attribute KWCa attribute EdlGaceFVIkarbMEbkeTACaEpñktUc²

teTAeTot)an. CaBiess attribute EbbenHeKGacbMEbk rWminbMEbkGaRs½yeTAtamtMrUvkar rbs;GñkeRbIR)as; database pÞal; ehIyCaTUeTAeKEtgEtbMEbk composite attribute

eTACa simple attribute eRBaHvamanPaBgayRsYlkñúgkarEsVgrk (easy to search). ]TahrN_ ³ Attribute Name KWCa Composite attribute eRBaHvaGac

eFVIkarbMEbkeTACa FirstName, MiddleName nig LastName )an. FirstName Name MiddleName LastName

EteyIgsegáteXIjfa attribute Name CaTUeTAeKeRcInEtbMEbkeTACa FirstName

nig LastName rWmineFVIkarbMEbkEtmþg BIeRBaHeyIgBuMTan;sa‘MueTAnwgkarbMEbkecjeRcIn EbbenHeT nigCaBiesseQμaHrbs;eyIgkMrman MiddleName Nas;. Attribute Address eyIgGacbMEbkeTACa HouseNo, StreetNo, Khan,

Province/City,.... HouseNo Address StreetNo Khan Province/City

C. Single-valued Attribute Single-valued Attribute is an attribute that holds a single value for a

single entity. Single-valued attribute KWCa attribute TaMgLayNaEdlbBa©ÚltMélEtmYyKt;

cMeBaHmYy single entity. ]TahrN_ ³ Attribute Sex én Students entity type eyIgGaceFVIkarbBa©Úl

Tinñn½y)anEtmYyKt; KW Male rW Female edayminGacbBa©ÚlTaMgBIr)aneT. eyIgdwg ehIyfamnusSmñak;EtgEtmanGayurbs;xøÜnEtmYyKt; )ann½yfa ebIGayu 18 KW 18

minGacniyayfa elakmñak;enaHmanGayudl;eTA 2 KW 18 nig 21 eT dUcenH attribute Age



én Students entity Ca single-valued attribute BIeRBaHeyIgGacbBa©Úl)anEtmYytMél Etb:ueNÑaHeT.

D. Multi-valued Attribute Multi-valued Attribute is an attribute that holds a multiple values for

a single entity. Multi-valued attribute KWCa attribute TaMgLayNaEdlGacbBa©ÚltMélCaeRcIn

cMeBaHmYy single entity. ]TahrN_ ³ Branch entity GacmanTUrs½BÞCaeRcIndUcCa 011 721727, 012

754155 nig 016 876312 dUcenHkñúgkrNIenH Tel_No Ca multiple-valued

attribute. Multi-valued attribute GacmansMnMutMélelxkMnt;BItMéltUcbMputeTAdl; tMélFMbMput (Multi-valued attribute may have a set of numbers with upper and

lower limits). ]TahrN_ ³ eK)ankMnt;fa Branch nImYy²mancMnYnTUrs½BÞBI 1 eTA 10

CaedIm. Staff entity man attribute Skill sMrab;kt;Rta Skill Edl Staff ecH ehIymüa:gvijeTotedaysar Staff Gacman Skill elIsBI 1 dUcCa C Programming

Language, Pascal Programming Language nig Visual Basic Programming

Language dUecñHkñúgkrNIenH Skill Ca multi-valued attribute. E. Derived Attribute Derived Attribute is an attribute whose values can be calculated from

related attribute values or a set of attributes values (plus possibly data not in the database, such as today’s date, the current time, or a security code provided by a system user).

Derived attribute KWCa attribute EdltMélrbs;vaKNnaecjBItMél attribute

mYy rWsMnuMén attributes ¬kñúgkrNImYycMnYn Tinñn½yenaHminsßitkñúg database dUcCa today’s date, the current time, or a security code pþl;eday system user¦.

]TahrN_ ³ Age attribute ekIteLIgedayeRbIR)as;GnuKmn_sMrab;KNnarkGayu eTAelI BirthDate attribute dUcenH attribute Age Ca derived attribute. Total_Staff attribute ekIteLIgBIkarrab; (count) eTAelI staffs TaMgGs;kñúg Staff entity.



Attribute Composite attribute Multi-valued attribute Derived attribute

STAFF

Staff_Name

DOB

Address

Staff_No

Sex FName

LName

Skill

SSN

Total_Staff

(rUb 4.4) Keys or Identifier eyIgcat;Tuk Key Ca data item EdlGaceFVIkarkMnt;GtþsBaØaNén entity enAkñúg

entity type. Key EckCa³ Candidate Key An attribute or set of attributes that uniquely

identifies individual occurrences of an entity type. Candidate key KWCa attribute mYy rWeRcInEdlGackMnt;GtþsBaØaNcMeBaH entity

nImYy²enAkñúg entity type. CaTUeTAenAkñúg entity type mYyGacman candidate key

elIsBI 1. ]TahrN_³ cMeBaH Staff entity type xagelI eyIgGackMnt;yk attribute eFVICa

candidate key )ancMnYn 2 KW Staff_No attribute rW SSN attribute. Primary Key The candidate key selected to be the primary key. Primary key KWCa candidate key 1 kñúgcMeNam candidate key TaMgGs;Edl

eyIgeRCIserIsCa primary key elIsBIenHeTotkñúg entity type mYyman primary key

EtmYyKt;. cMeBaH entity type Edlman candidate key elIsBI 1 Gñkksag database

RtUvEteRCIserIsmYykñúgcMeNamenaHmkeFVICa primary key. manlkçxNÐmYycMnYn kñúgkareRCIserIs primary key:

tMélelI primary key attribute kMrnwgERbRbYl. tMélelI primary key attribute CatMélRtwmRtUv (valid value) nigminpÞúktMél

Null (or unknown).



eCosevogkareRbI intelligent key Edlmanrcnasm<½n§bBa¢ak;BIcMNat;fñak; (classification), TIkEnøg (location)...... ]TahrN_³ 2 tYGkSrdMbUgéntMél primary

key sMrab;bBa¢ak;BI warehouse location. BicarNaeTAelIkarCMnYs large composite key eday primary key EdlekIt

eLIgEt 1 attribute. ]TahrN_³ Game_Number attribute én Game entity type

KYrEtGaceRbICMnYs composite key ekItBI Home_Team nig Visiting_Team. ]TahrN_³ cMeBaH Staff entity type xagelI eyIgGaceRCIserIs candidate key

mYykñúgcMeNamenaH KW Staff_No attribute eFVICa primary key nig candidate key

SSN Edlmin)aneRCIerIsCa primary key eKeGayeQμaHfa alternate key. Composite Key A candidate key that consists of two or more

attributes. Composite key KWCa candidate key EdlpSMeLIgeday attributes 2 rWeRcIn. ]TahrN_³ cMeBaH Student_Course entity type Edlman attributes dUcCa

Student_ID, Course_ID, Date_Start, Date_Complete, Grade. edayehtufa Student mñak;GacsikSa Course EtmYydUcKñakñúgeBlxusKña Et Course mYyGacman Student CaeRcInsikSakñúgeBlEtmYy dUcenHeyIgGackMnt;)an candidate key mYycMeBaH entity type enHEdlekIteLIgeday 3 attributes KW Student_ID, Course_ID nig Date_Start dUcenHeKniyayfa Student_Course entity type man composite key

mYyekItBI 3 attributes.

1. 3. Relationship Types (Relationship Sets) Relationship is an association among the instances of one or more entity types that is of interest to the organization. Relationship KWCakarcgTMnak;TMngrvag instances én entity type 1 rWeRcInEdl manplRbeyaCn_cMeBaH organization. Relationship type (Relationship set) is a collection of relationship. Relationship type KWsMnMuén relationship. Relationship instance or Relationship occurrence is a single occurrence of a relationship type. Relationship instance rW Relationship occurrence KWsMedAelIkarelceLIg rWbgðajEtmþgkñúg relationship type.



]TahrN_³ ]bmafa eyIgman entity types cMnYn 2 KW Employee nig Course

ehIy Course mYyGacman Employee CaeRcInsikSa nigbBa©b;vKÁ RBmTaMg Employee

mñak;GacsikSa nigbBa©b; Course CaeRcIn. edIm,Itamdan Course NaxøHEdl Employee

)anbBa©b;vKÁ eyIgeFVIkarkMnt; relationship rvag Employee nig Course entity types.

(rUb 4.5)

EMPLOYEE

Employee_Name

BirthDate

COURSE

Course_Title

Relationship type

Employee_ID Course_ID

Completes

Date_Complete

Degree of a Relationship is the number of entity types that participate in a relationship. Degree of Relationship KWCacMnYn entity types EdlcUlrYmkñúg relationship

enaH. Entity type EdlcUlrYmkñúg relationship enaHeKeGayeQμaHfa participants. Degree of relationship EckCa 4 KW Unary relationship A relationship where the same entity participates

more than once in different roles. Unary relationship KWCa relationship Edl entity dUcKñacUlrYmelIsBImþgeday edIrtYnaTIepSgKña. karkMnt;eQ μaHtYnaTI (role name) mansarHsMxan;Nas;kñúg unary

relationship (rWGacehAmüa:geTotfa recursive relationship) edIm,IkMnt;muxgar (function) rbs; entity kñúgkarcUlrYmenaH. ]TahrN_³ cMeBaH Staff entity type Edlman relationship ekIteLIgEtkñúg entity xøÜnÉgmYyeQμaHfa Supervises eBlenaHeyIgRtUvEtkMnt;muxgareTAeGay entity

EdlcUlrYm. manmuxgar 2 KW Supervisor nig Supervisee Edlbgðajfa Supervisor

eFVIkarRKb;RKgelI Supervisee rW Supervisee sßiteRkamkarRKb;RKgrbs; Supervisor.



STAFF

Supervises

Supervisor Supervisee

(One-to-Many) (One-to-Many)

Supervisor

Supervisee

STAFF Supervises

(One-to-One)

PERSON

Is_married_to

Husband Wife

COURSE

Requires

(Many-to-Many) (rUb 4.6)

Binary relationship A relationship between the instances of two entities.

Binary relationship KWCa relationship rvag instances én 2 entities. Binary

relationship KWCa relationship EdlCYbRbTHeRcInCageKkñúgkarksag database.



]TahrN_³ rUbxageRkambgðajBI relationship EdlekItmancMeBaH Student eFVIkar cuHeQμaH (register) elI Course.

EMPLOYEE DEPARTMENT Manages (One-to-One)

OWNER PROPERTY Owns (One-to-Many)

(Many-to-Many)

STUDENT COURSE Registers_for

(rUb 4.7) Ternary relationship A relationship between the instances of three

entities. Ternary relationship KWCa relationship rvag instances én 3 entities. ]TahrN_³ Relationship Interviews cMeBaHrUbxageRkambgðajsßankarN_Edl Staff mYycMnYnTTYlbnÞúkkñúgkareFVIsMPaseTAelI Client eTAtam Room Edl)ankMnt;.

(rUb 4.8)

CLIENT ROOM Interviews

STAFF

Quaternary relationship A relationship between the instances of four entities.

Quaternary relationship KWCa relationship rvag instances én 4 entities. ]TahrN_³ Relationship Arranges cMeBaHrUbxageRkambgðajsßankarN_Edl GñkTij (Buyer) EdlTTYlkarENnaMBIsμakþI (Solicitor) eRkamkareRCamERCgBI sßab½nhirBaØvtßú (Financial Institution) dak;tMéledjéfø (Bid) eTAelI Property.



(rUb 4.9)

BUYER FINANCIAL INSTITUTION

Arranges

SOLICITOR

BID

1. 4. Attributes on Relationships

Attributes GaceFVIkarP¢ab;eTAkan; relationship CaBiesscMeBaHTMnak;TMng Many-to-Many edIm,IbBa¢ak;Gtßn½yeGaykan;Etc,as;EfmeTot. ]TahrN_³ cMeBaH Date_Complete attribute xagelIP¢ab;eTAkan; relationship Completes edIm,Ibgðaj GMBIkalbriecäTEdl Employee )anbBa©b;karsikSaeTAelI Course. 2. Structural Constraints eBlenHeyIgRkeLkemIleTAelI constraint kMnt;eTAelI entities Edl)ancUlrYm kñúg relationship vijmþg. Constraints KYrEtbgðajBIkardak;kMrit (restrictions) eTAelI relationship dUceTAnwgkargarCak;EsþgEdleyIgEtgEtCYbRbTH. ]TahrN_eTAelI constraint EdlKitfa ral; property RtUvEtman owner nigRKb; branch office dac;xat RtUvEtmanbuKÁlikya:gehacNas;mñak;eFVIkarEdrCaedIm. kardak;kMriteTAelI relationship

EckCa 2 RbePTKW Cardinality and Participation Constraints.

2. 1. Cardinality Constraints Cardinality ratio Describes the number of possible relationships for

each participating entity. Cardinality ratio bgðajBIcMnYnTMnak;TMngEdlGacekItmancMeBaH entity cUlrYm nImYy². Cardinality ratio cMeBaH relationship EckCa 3 RbePTeTotKW One-to-One

(1:1), One-to-Many (1:M) nig Many-to-Many (M:N).



Cardinality ratio rvag entities KWCaeKalkarN_EdlkMnt;enAkñúg organization

edIm,IeGayskmμPaBkargardMeNIr)anRtwmRtUv ehIyeKalkarN_enaHeKeGayeQμaHehAfa business rules. Business rules bgðajCaEpñkd¾sMxan;mYykñúg modeling ehIyminEmn RKb; business rules TaMgGs;suT§EtGacbgðajkñúg ER diagram eT. ]TahrN_eTAelI business rules EbbenaH KWtMrUvkarEdlsmaCik staff TTYl)anéf¶Qb;sMrakbEnßmeTot (additional day’s holiday) erogral;qñaM. One-to-One Relationship sMedAeTAelI entity 1 kñúg entity type A manTMnak;TMngCamYy entity ya:geRcIn bMput 1 kñúg entity type B ehIy entity 1 kñúg entity type B manTMnak;TMngCamYy entity ya:geRcInbMput 1 kñúg entity type A vij.

A1

A2

A3

A4

(A)

B1

B2

B3

(B)

(rUb 4.10)

enAkñúgrUb 4.7 man binary relationship Manages EdltP¢ab;TMnak;TMngrvag Employee entity nig Department entity. Rkumh‘unmaneKalkarN_fa Employee

mñak;GaceFVIkarRKb;RKg)anEtmYy Department b:ueNÑaH ehIy Department mYymanEt Manager RKb;RKgEtmñak;Kt;. eyIgsegáteXIjfa TMnak;TMngenHCa TMnak;TMng One-to-

One.

(One-to-One)

EMPLOYEE DEPARTMENT Manages 1 1

(rUb 4.11)



One-to-Many Relationship sMedAeTAelI entity 1 kñúg entity type A manTMnak;TMngCamYy entity 1 rWeRcInkñúg

entity type B. eTaHbICaya:gNak¾eday entity 1 kñúg entity type B manTMnak;TMng CamYy entity ya:geRcInbMput 1 kñúg entity type A vijEtb:ueNÑaH.

A1

A2

A3

(A)

(B)

B1

B2

B3

B4

B5

(rUb 4.12)

enAkñúgrUb 4.7 man binary relationship Owns EdltP¢ab;TMnak;TMngrvag Owner

entity nig Property entity. Rkumh‘unmaneKalkarN_fa Owner mñak;Gacman Property

CaeRcInCaRTBüsm,tþrbs;xøÜn ehIy Property mYymanEt Owner Etmñak;Kt;RKb;RKgEt b:ueNÑaH. eyIgsegáteXIjfa TMnak;TMngenHCaTMnak;TMng One-to-Many.

OWNER PROPERTY Owns 1 M

(One-to-Many) (rUb 4.13)

Many-to-Many Relationship sMedAeTAelI entity 1 kñúg entity type A manTMnak;TMngCamYy entity 1 rWeRcInkñúg entity type B ehIy entity 1 kñúg entity type B manTMnak;TMngCamYy entity 1

rWeRcInkñúg entity type A vijEdr.



A1

A2

A3

A4

(A)

B1

B2

B3

B4

(B)

(rUb 4.14) enAkñúgrUb 4.7 man binary relationship Registers_for EdltP¢ab;TMnak;TMng rvag Student entity nig Course entity. salamaneKalkarN_fa Student

mñak;GaccuHeQμaHsikSaeTAelI Course )aneRcIn ehIy Course mYyman Student sikSa CaeRcIn. eyIgsegáteXIjfa TMnak;TMngenHCaTMnak;TMng Many-to-Many.

(Many-to-Many)

STUDENT COURSE Registers_for M N

(rUb 4.15)

2. 2. Participation Constraints Participation Constraint Determines whether the existence of an

entity depends upon it being related to another entity through the relationship.

Participation constraint kMnt;faetIkarekItman entity NamYyGaRs½yBwgBak; eTAelIkarTak;TgCamYy entity epSgeTotkñúg relationship.

Participation constraint EckCa 2 RbePTKW total nig partial. Participation

manlkçN³ total RbsinebIkarekItmanén entity NamYyTamTarkarekItmanén entity

epSgeTotkñúg relationship ebIBuMdUecñaHvamanlkçN³ partial. Participation enAkñúg relationship P¢ab;KñaedaybnÞat; (line) EdlbnÞat;mYy (single line) bgðajBIlkçN³ partial ehIybnÞat;BIr (double line) bgðajBIlkçN³ total.

Bakü total nig partial participation CYnkalGacsMedACa mandatory nig optional participation.



]TahrN_³ cMeBaH Branch IsAllocated Staff relationship enAkñúgrUbxageRkam ral; branch office EtgEtmansmaCik staff Canic© eBlenaH participation én Branch

entity manlkçN³ total. eTaHbICaya:gNak¾eday smaCikmYycMnYnén staffs

(]TahrN_/ Sales Personnel) GacminsßitenAkñúg branch office NamYyesaHenAkñúg IsAllocated relationship dUcenH participation én Staff entity manlkçN³ partial. (rUb 4.16)

Branch Staff IsAllocated 1 M

Branch_No Staff_No

eyIgGaceRbIR)as;sBaØaCMnYs (alternative notation) sMrab;bgðaj structural

constraint enAkñúg relationship edayeFVIkarbgðajtMéltUcbMput (minimum value) nig tMélFMbMput (maximum value) Cab;nwgExSbnÞab;tP¢ab; (connecting line) sMrab;bgðajBI participation én entity enAkñúg relationship. ]TahrN_³ eyIgeRbIR)as; notation edIm,IbgðajBI structural constraints enAkñúg Branch IsAllocated Staff relationship dUcrUbxageRkamenH. plRbeyaCn_énkareRbI R)as; notation GacbgðajBIB½t’manbEnßmeToteTAelI constraint enAkñúg relationship. (5, N) notation rvag Branch entity nig IsAllocated relationship bBa¢ak;fa ya:gehacNas; staffs 5 nak;sßitkñúg branch office nImYy² (Min = 5) ehIykñúg branch office nImYy²man staffs minkMnt; (Max = N). dUcKñaenHEdr (0, 1) notation

rvag Staff entity nig IsAllocated relationship bBa¢ak;fa staff mñak;Gacminsßitkñúg branch office NamYy Tal;EtesaH (Min = 0) nig staff mñak;Gacsßitkñúg branch

office ya:geRcInbMput 1 (Max = 1). (rUb 4.17)

Branch Staff IsAllocated

Branch_No Staff_No

(5, N) (0, 1)



3. The Enhanced Entity-Relationship Model Entity-Relationship Model (ER Model) manlkçN³RKb;RKan;sMrab;bgðaj

database schema TUeTAPaKeRcIncMeBaH traditional nig administrative-based

database b:uEnþcab;taMgBIqñaM 1980 mkmankarrIkcMerInya:gxøaMgkñúgkarGPivDÆn_ database

fμI²EdlmanlkçN³sμúKsμajsaMujaMuEdl ER Model BuMGacbMeBj)an eTIbbNþaleGayeK eFVIkarEksMrYledaybEnßmlkçN³mYYycMnYneTAelI ER model edIm,IeFVIeGayvaGacbgðaj Tinñn½ysμúKsμajkñúgeBlbc©úb,nñenHeGay)anRtwmRtUv edaydak;eQ μaHfa Enhanced

Entity-Relationship Model (EER Model). EER Model The model that has resulted from extending the original

ER model with new modeling constructs. EER model KWCa model EdlekItecjBIkarbEnßmlkçN³mYycMnYneTAelI ER

model EdlmanRsab;. Modeling construct fμIehIymansarHsMxan;bMputEdl)anbBa©ÚlenAkñúg EER

model KW Supertype/Subtype relationship.

3. 1. Supertypes (Superclasses) and Subtypes (Subclasses) Subtype A subgrouping of the entities in an entity type which has

attributes that are distinct from those in other subgroupings.

Subtype KWCabNþúMrg entity enAkñúg entity type Edlman Attributes xusBI bNþúMrgepSgeTot. CaTUeTAenAkñúg EER model, subtype EtgEtmantYnaTI (distinct

role) c,as;las;xusBI subtype d¾éTeTot. Supertype An generic entity type that has a relationship with one or

more subtypes. Supertype KWCa entity type TUeTAEdlmanTMnak;TMngCamYy subtypes mYy rWeRcIn.

enAkñúgkrNImYycMnYn entity type mYyRbEhlCaGacman subtypes CaeRcInEdl mantYnaTIxus²Kña. ]TahrN_³ Entities EdlCasmaCikén Staff entity type Gac cat;CaRkumeTAtamtYnaTICa Manager, Secretary nig Sales Personnel

EdlkñúgenaHeKcat;Tuk Staff entity set Ca supertype én subtypes: Manager,

Secretary nig Sales Personnel. Relationship EdlekIteLIgrvag supertype mYynig



subtype NamYykñúgcMeNam subtype TaMgGs; eKehAfa Supertype/Subtype

relationship (Superclass/Subclass relationship). ]TahrN_³ Staff/Manager KWCa supertype/subtype relationship.

ral;smaCikén subtype k¾KWCasmaCikén supertype pgEdr. elIsBIenHeTAeTot smaCikén subtype KWdUceTAnwg entity enAkñúg supertype b:uEnþmantYnaTIxusKña (Each member of a subtype is also a member of the supertype. In othe words, the subclass member is the same as the entity in the supertype, but has a distinct role.). b:uEnþmansmaCikmYycMnYnén supertype GacminEmnCasmaCikén subtype

NamYyTal;EtesaH. Relationship rvag supertype nig subtype KW One-to-One

(1:1) relationship. manehtuplsMxan; 2 EdlnaMeGaymankarEnnaMeGaysÁal;nUv concepts én

supertypes and subtypes KW - ehtuplTI 1: eCosvagkarBN’na concepts RsedogKñaeRcInelIkeRcInsar

edayehtuenHehIy eFVIeGaykat;bnßyeBlevlakñúgkarksag nigeFVIeGayeyIgemIl ER

diagram kan;Etqab;yl; (The first reason is that it avoids describing similar concepts more than once, thereby saving time for the designer and making the ER diagram more readable.).

- ehtuplTI 2: bEnßmB½t’manEfmeToteTAkan;karksagkñúgTMrg;mYyEdlmnusSPaK eRcInGacdwg rWsÁal;ya:gc,as; (The second reason is that it adds more semantic

information to the design in a form that is familiar to many people. ).

3. 2. Attribute Inheritance Subtype entity inherits values of all attributes of the supertype. Subtype entities eFVIkarTTYlykral; attributes TaMgGs;én Supertype. ]TahrN_³ Sales_Personnel subtype TTYlykral; attributes TaMgGs;én

Staff supertype dUcCa Staff_No, Name, Address nig DOB RBmTaMg attributes

pÞal;rbs;vadUcCa Car_Allowance nig Sales_Area. Subtype KWCa entity edayehtudUcenHvaRbEhlCaGacman subtypes Carbs;va

pgEdr. An entity, and its subtypes, and their subtypes, and so on, is called a

type hierarchy. eQμaHEdleKkMnt;eTAelI type hierarchy mandUcCa³



specialization hierarchy (]TahrN_³ Manager is a specialization of staff),

generalization hierarchy (]TahrN_³ Staff is a generalization of Manager) nig IS-A hierarchy (]TahrN_³ Manager IS-A (member of) Staff).

Sales_ Personnel

Car_ Allowance Bonus

Manager

Secretary

O

Typing_ Speed

Sales_ Area

Staff

Address

Sex

Staff_No

Name

FName LName

IsAllocated

Branch

IsAllocated

1

1

1 M

(rUb 4.18)

3. 3. Specialization Specialization The process of maximizing the differences between

members of an entity by identifying their distinguishing characteristics.

Specialization KWWCaRbtibtþikarkñúgBRgIkPaBxusKñarvagsmaCikén entity edayeFVI karkMnt;lkçN³xusEbøkKñarbs;BYkva. Specialization CaRbtibtþikarBIelIcuHmkeRkam (top-down process) kñúgkarkMnt;sMnMuén supertypes nig subtypes rbs;BYkeK ehIykarkMnt;sMnuMén subtypes edayQreTAelImUldæanénlkçN³xusEbøkKña (distinguishing characteristics) én entities enAkñúg supertype. bnÞab;BIeyIg



kMnt;)ansMnMu subtypes én entity type rYcmk eyIgeFVIkarP¢ab; specific attributes

eTAkan; subtype nImYy² (enAeBlcaM)ac;) nigkMnt; relationship pgEdrrvagral; subtypes nImYy² nig entity types rW subtypes d¾éTeTot (enAeBlcaM)ac;). ]TahrN_³ eFVIkarRtYtBinitüeTAelI specialization EdlkMnt;sMnMu subtypes rYmman Manager, Secretary nig Sales Personnel ecjBI Staff supertype. eyIgeRbIR)as; EER diagram edIm,IbgðajCarUbsMKal; specialization dUcrUb 4.18. eyIgkt;sMKal; eXIjfa Staff supertype nig subtypes epSgeTotbgðajCaragctuekaNEkg (rectangle) ehIy subclasses én specialization P¢ab;eTAkan;rgVg;mUl (circle) tamryH bnÞat;mYy (single line) ehIybnÞat;enaHk¾P¢ab;eTAkan; supertype teTAeTot. Subset

symbol or U-Shaped symbol ( ⊂ ) sßitenAelIbnÞat;enaHsMrab;bBa¢ak;BITisedAén supertype/subtype relationship (]TahrN_³ Manager ( ⊂ ) Staff). sBaØa ‘O’

enAkñúg specialization circle bgðajBI constraints elI supertype/subtype

relationship. Specific attributes P¢ab;eTAkan; subtypes rbs;eK ]TahrN_³ dUcCa Car_Allowance nig Sales_Area kñúgrUb 4.18 EdlP¢ab;eTAkan; Sales_Personnel

subtype EtmYyKt;. eyIgRbEhlCaGacman specializations mYycMnYneTAelI entity EtmYyedayQr mUldæaneTAelIlkçN³xusEbøkKña. ]TahrN_³ cMeBaHrUbxageRkam (rUb 4.19) bgðajBI specialization mYyepSgeTot EdlbegáIt subtypes 2 eTotKW Full_Time_Permanent

nig Part_Time_Temporary edayEbgEcklkçN³xusKñaelIkic©snüakarCYlrbs;buKÁlik (employment contract). tamryHrUbenH eyIgk¾bgðajBI specific attributes én Full_Time_Permanent

(Salary_Scale nig Holiday_Allowance) nig Part_Time_Temporary

(Hourly_Rate) subtypes. sBaØa ‘d’ kñúg specialization circle bgðajBI constraints

elI supertype/subtype relationship.



d

Bonus

Manager

Secretary

O

Typing_ Speed

Sales_ Personnel

Car_ Allowance

Sales_ Area

Staff

Address

Sex

Staff_No

Name

FName LName

IsAllocated

Branch

IsAllocated

1 M

(rUb 4.19) 3. 4. Generalization

Generalization The process of minimizing the differences between entities by identifying their common features.

Generalization KWWCaRbtibtþikarkñúgbRgYmPaBxusKñarvagsmaCikén entity edayeFVI karkMnt;lkçN³TUeTArbs;BYkva. Specialization CaRbtibtiþkarBIeRkameLIgelI (bottom-

up process) edayeFVIkarkMnt; generalized supertype ecjBI original subtypes. Rbtibtþikarén generalization manlkçN³pÞúyBI specialization. ]TahrN_³ eFVIkarRtYtBinitüeTAelI Manager, Secretary nig Sales Personnel

EdlbgðajCa entities dac;edayELkBIKña. RbsinebIeyIgeFVIRbtibtþikar generalization

eTAelI entities TaMgenaH KWeyIgcg;kMnt;PaBdUcKñarvagBYkvadUcCa common attributes

nig relationships. dUc)anerobrab;BIxagelI entities TaMgenHeRbIR)as; common

1

1

Part_Time Temporary

Full_Time Permanent

Salary_ Scale

Holiday_ Allowance

Hourly_ Rate



attributes cMeBaH staffs TaMgGs; ehIyehtudUecñHeyIgnwgkMnt; Manager, Secretary nig Sales_Personnel Ca subtypes én supertype Staff dUcrUb 4.18.

3. 5. Constraints on Specialization and Generalization enAkñúgcMnucenH eyIgnwgBN’naGMBI constraints EdlkMnt;eTAelI specialization rW generalization. Constraint TI 1 ehAfa Disjoint constraint. Constraint enHkMnt;fa RbsinebI subtypes én specialization manlkçN³ disjoint enaH entity GacCasmaCik én subtype mYykñúgcMeNam subtypes TaMgGs;én specialization (This constraint specifies that if the subtypes of a specialization are disjoint, then an entity can be a member of only one of the subtypes of the specialization.). sBaØatMNag eGay disjoint constraint tagedaytYGkSr ‘d’ (mann½yfa disjoint) dak;kñúgrgVg;mUl (circle) EdlP¢ab; subtypes eTAkan; supertype. Subtypes cMeBaH specialization

kic©snüakñúgkarCYl (Full_Time_Permanent, Part_Time_Temporary) kñúgrUb 4.19

bgðajBI disjoint constraint mann½yfa kic©snüakñúgkarCYlcMeBaHsmaCikén staff

ebIminmanlkçN³ full-time permanent KWmanlkçN³ part-time temporary

KWminGacmanlkçN³TaMg 2 kñúgeBlEtmYy)aneT. RbsinebI subtypes én specialization KμanlkçN³ disjoint enaHmann½yfa entity GacCasmaCikén subtype kñúg specialization elIsBI 1 (If subtypes of a specialization are not disjoint, then an entity may be a member of more than one subtype of a specialization.). edIm,IbgðajBI nondisjoint constraint

eKeRbItYGkSr ‘o’ (mann½yfa overlapping) dak;kñúgrgVg;mUl (circle) EdlP¢ab; subtypes

eTAkan; supertype. Subtypes cMeBaH specialization tYnaTIkargar (Manager,

Secretary, Sales_Personnel) kñúgrUb 4.19 bgðajBI nondisjoint constraint mann½yfa staff mYyGacCasmaCikén Manager nig Sales_Personnel subtypes TaMg 2 Etmþg. Constraint TI 2 elI specialization ehAfa participation constraint

EdlGacCa total rW partial. Specialization Edlman total participation kMnt;fa ral; entity nImYy²enAkñúg supertype RtUvEtCasmaCikén subtype kñúg specialization (A specialization with a total participation specifies that every entity in the



supertype must be a member of a subtype in the specialization.). edIm,IbgðajBI total participation eKeRbIExSbnÞat;BIr (double line) KUrP¢ab;BI supertype eTAkan; specialization circle. enAkñúgrUb 4.19 kic©snüakñúgkarCYlmanlkçN³ total

participation Edlmann½yfa ral;smaCikTaMGs;én staff suT§Et part-time rW full-time. Specialization cMeBaH partial participation kMnt;fa entity mYymincaM)ac;Ca kmμsiT§ rWCasmaCikén subtypes NamYyTal;EtesaHkñúgcMeNam subtypes TaMgGs;eT (A specialization with partial participation specifies that an entity need not belong to any of the subtypes of a specialization.). Partial participation

bgðajedayExSbnÞat;mYy (single line) KUrP¢ab;BI supertype eTAkan; specialization

circle. enAkñúgrUb 4.19 specialization tYnaTIkargarmanlkçN³ partial participation Edlmann½yfa smaCikén staff mincaM)ac;mantYnaTIkargarbEnßmeToteTdUcCa Manager,

Secretary or Sales_Personnel. karcUlrYmKñarvag disjoint nig participation constraints )anbegáItCa 4 RbePTKW disjoint and total, disjoint and partial, overlapping and total nig overlapping

and partial. 4. Transforming EER Diagrams into Relations

eRkayBIbegáIt EER diagram rYc eyIgRtUvbMElgvaeTACa relations (tables)

edayeRbIR)as;sMnMuénc,ab;mYycMnYnsMrab;kMnt;dUcteTA³ Step 1: Map Regular Entities ral; entity type FmμtaTaMgGs;enAkñúg ER diagram RtUvbMElgeTACa relation

(table) ehIyeQ μaH relation dUcnwgeQμaH entity type. ral; simple attribute TaMgGs; én entity type nwgbMElgeTACa attribute én relation elIsBIenHeTot key rW identifier

én entity type nwgbMElgeTACa primary key én relation.

Staff_No STAFF

Name Sex

Address



(rUb 4.20a) Staff (Staff_No, Name, Sex, Address) (rUb 4.20b)

Composite Attributes enAeBleFVIkarbMElgcMeBaH entity FmμtaEdlman composite attribute eyIgKYrEtbBa©Úl simple attributes TaMgGs;EdlCabMENkén composite attribute eTAkan; relation rWrkSaEt composite attribute enaH b:uEnþviFIEdl eKeRbIR)as;jwkjab;CageKKWbBa©Úl simple attributes TaMgGs;én composite attribute

eTAkan; relation.

(rUb 4.21a) Staff (Staff_No, Name, Sex, HouseNo, StreetNo, Province) (rUb 4.21b)

Multivalued Attributes enAeBleFVIkarbMElgcMeBaH entity FmμtaEdlman multivalued attribute eyIgRtUvEtbMElgvaeTACa 2 relations eday relation TI 1pÞúknUv simple attributes TaMgGs;én entity type elIkElgEt multivalued attribute ehIy relation TI 2 pÞúk attributes cMnYn 2 Edl attribute 1 kñúgcMeNamenaHKWCa primary key

én relation TI 1 nig attribute 1 eTotKWCa multivalued attribute elIsBIenHeTot primary key én relation TI 2 pSMeLIgeday attributes TaMg 2 enH.

(rUb 4.22a) Staff (Staff_No, Name, Sex Address) Staff_Skill (Staff_No, Skill) (rUb 4.22b)

Staff_No

Province

STAFF

Name Sex

Address

HouseNo StreetNo

STAFF

Name

Staff_No

Sex

Skill

Address



Step 2: Map Weak Entities eKeFVIkarbMElg weak entity edayeFVIkarbegáIt relation fμImYypÞúk simple

attributes TaMgGs;én weak entity RBmTaMg primary key én identifying owner Edl attribute enaHnwgkøayeTACa foreign key. Primary key én relation fμIenHpSMeday primary key én identifying owner rYmCamYy partial key én weak entity.

(rUb 4.23a) Employee (Employee_ID, Employee_Name) Dependent (Employee_ID, Dependent_Name, Sex, BirthDate) (rUb 4.23b)

Has EMPLOYEE

Employee_Name

Employee_ID Dependent_Name BirthDate

DEPENDENT

Sex

Step 3: Map Binary Relationships Cardinality ratio cMeBaH binary relationship EckecjCa 3 RbePTeTotKW

One-to-One, One-to-Many nig Many-to-Many. Map Binary One-to-Many Relationships eKeFVIkarbMElg binary 1:M relationship edaybegáIt relation epSg²KñasMrab;

entity types TaMg 2 Edl)ancUlrYmenAkñúg relationship. bnÞab;mkbEnßm primary key

én one-side entity eTAkan; many-side entity edIm,IeGayvakøayeTACa foreign key

eTIb relations TaMg 2 GaceFVIkarTak;TgKña)an.

CUSTOMER

Customer_Name

Address

ORDER

Order_Date Customer_ID Order_ID

Submits

(rUb 4.24a)



Customer (Customer_ID, Customer_Name, Address) Order (Order_ID, Order_Date, Customer_ID) (rUb 4.24b) Map Binary Many-to-Many Relationships eKeFVIkarbMElg binary M:N relationship edaybegáIt relation epSg²KñasMrab;

entity types TaMg 2 Edl)ancUlrYmenAkñúg relationship nigbegáIt relation fμImYy epSgeTotedaypÞúk primary key én relations TaMg 2 ehIy attributes TaMg 2 enaH PaKeRcIn eRcInEtcUlrYmpSMKñaeFVIkarCa primary key én relation fμIenaH.

EMPLOYEE

Employee_Name

BirthDate

COURSE

Course_Title Employee_ID Course_ID Completes

Date_Complete Result

(rUb 4.25a)

Employee (Employee_ID, Employee_Name, BirthDate) Course (Course_ID, Course_Title) Completes (Employee_ID, Course_ID, Date_Complete, Result) (rUb 4.25b)

Map Binary One-to-One Relationships

eKeFVIkarbMElg binary one-to-one relationship edayGnuvtþCa 2 CMhan. CMhanTI 1 RtUveFVIkarbegáIt relation nImYy²sMrab; entity types TaMg 2nigCMhanTI 2 Taj primary key én relation NamYyeTAdak;kñúg relation mYyeTotedIm,IkøayeTACa foreign

key.



(rUb 4.26a)

Employee (Employee_ID, Employee_Name, Address) Department (Dept_ID, Dept_Name, Phone, Mgr_ID) (rUb 4.26b) Step 4: Map Unary Relationships Cardinality ratio cMeBaH unary relationship EckecjCa 3 RbePTeTotKW

One-to-One, One-to-Many nig Many-to-Many. Map Unary One-to-One and One-to-Many Relationships eKeFVIkarbMElg unary 1:M relationship edaybegáIt relation mYyedaybBa©Úl

simple attributes TaMgGs; bnÞab;mkbEnßm foreign key eTAkan; relation dEdlenaH Edlcg¥úl rWTajtMél (references) eTAkan; primary key enAkñúg relation EtmYy.

(rUb 4.27a) For One-to-One relationship Person (Person_ID, Name, Sex, Address, Partner_ID) (rUb 4.27b)

EMPLOYEE

Employee_Name

Address

DEPARTMENT

Phone Employee_ID Dept_ID

Manages

Dept_Name

PERSON

Name

SexPerson_ID

Married

Address



(rUb 4.28a) For One-to-Many relationship Staff (Staff_ID, Staff_Name, Address, Supervisor_ID) (rUb 4.28b)

STAFF

Staff_Name

AddressStaff_ID

Supervises

Map Unary Many-to-Many Relationships eKeFVIkarbMElg unary M:N relationship edaybegáIt relation fμIcMnYn 2 eday

relation TI 1bgðajBI entity type enAkñúg relationship ehIy relation mYyepSgeTot bgðajBITMnak;TMng M:N CamYyxøÜnÉgpÞal;.

(rUb 4.29a) Course (Course_ID, Description, Credit) Course_Pre (Course_ID, Pre_Take) (rUb 4.29b)

COURSE

Description

CreditCourse_ID

Requires



Step 5: Map Ternary, Quaternary and n-ary Relationships eKeFVIkarbMElg ternary, quaternary and n-ary relationship edaybegáIt

relation epSg²KñasMrab; entity types EdlcUlrYmkñúg relationship nigbegáIt relation fμI mYyeTotedaypÞúk primary key én relations TaMgenaH kñúgkrNImYycMnYn attributes

TaMgenaHnwgkøayeTACa primary key sMrab; relation fμIenaH.

(rUb 4.30a)

Patient (Patient_ID, P_Name) Physician (Physician_ID, Phy_Name) Treatment (Treatment_Code, Description) Patient_Treatment (Patient_ID, Physician_ID, Treatment_Code, Date,

Result)

PATIENT

Patient_ID P_Name

PHYSICIAN

Physician_ID Phy_Name

TREATMENT Treatment_Code Description

Patient Treatment

Date

Result

(rUb 4.30b) Step 6: Map Supertype/Subtype Relationships manviFICaeRcInkñúgkarbMElg supertype/subtype relationship eTACa relations

b:uEnþminTan;manviFINamYyeKcat;TukCa standard enAeLIy b:uEnþeyIgelIkykviFINaEdl eKeRbIR)as;jwkjab;CageKEtb:ueNÑaH.

1. begáIt relation nImYy²sMrab; supertype nig subtypes nImYy² 2. bBa©Úl common attributes eTAkan; supertype relation edayrYmTaMg

primary key pgEdr



3. bBa©Úl primary key én supertype relation eTAkan; subtype relation

nImYy² RBmTaMg specific attributes cMeBaH subtype relation nImYy² 4. bBa©Úl attribute 1 (rWeRcIn) eTAkan; supertype eGayedIrtYnaTICa subtype

discriminator Subtype discriminator KW attribute sßitkñúg supertype entity EdltMélrbs;va

eRbIR)as;sMrab;bg¥úl rWbgðajBI subtype. kñúgkrNIEdl relationship manlkçN³ disjoint eBlenaHeKeRbIR)as; subtype

discriminator EtmYyehIytMélvaeRbIR)as;sMrab;cg¥úl subtype ]TahrN_³ tamryHrUb 4.31a eyIgeXIjfa ebIeyIgbBa©ÚltYGkSr “M” eTAkan; subtype discriminator mann½y fa hardware enaHmanRbePTCa Mouse b:uEnþebIbBa©ÚltYGkSr “K” mann½yfa hardware

enaHmanRbePTCa Keyboard ehIyebIbBa©ÚltYGkSr “H” vij mann½yfa hardware

enaHmanRbePTCa Hard disk.

Hard-Disk

Buttons

Mouse

Keyboard

D

Keys Size

Hardware

Made Year

Hardware ID

Model

H_Type

H_Type =

“M”

“K”

“H” Subtype discriminator

(rUb 4.31a)



Hardware (Hardware_ID, Made_Year, Model, H_Type) Mouse (Hardware_ID, Buttons) Keyboard (Hardware_ID, Keys) Hard_Disk (Hardware_ID, Size) (rUb 4.31b)

pÞúyeTAvij RbsinebI relationship manlkçN³ overlap eKRtUveRbIR)as; subtype

discriminator elIsBImYy ehIy subtype discriminators TaMgenaHGacpÞúktMél)anEt 2

Kt;KW True nig False. ]TahrN_³ tamryHrUb 4.32a eyIgeXIjfa ebIeyIgbBa©Úl staff

NamYyEdlmantYnaTIdl;eTA 2 Ca Manager nig Sale Personnel enaHeyIgRtUv bBa©ÚlcMeBaH record enaHnUv MFlag esμI True ehIIy SFlag esμI False nig PFlag esμI True.

O

STAFF

Name

Staff ID

Sex

S_Type

S_Type =

Address

Sale_

Bonus

Manager

Secretary

Typing_SpeedSale_ Area

Car_ Allowance

Manager?=”Y” Sale Personnel?=”Y”

Secretary?=”Y”

Manager?

Secretary?

Sale Personnel?

(rUb 4.32a)



Staff (Staff_ID, Name, Sex, Address, MFlag, SFlag, PFlag) Manager (Staff_ID, Bonus) Secretary (Staff_ID, Typing_Speed) Sale_Personnel (Staff_ID, Sale_Area, Car_Allowance)

(rUb 4.32b) Review Questions

1. cUrBnül;eGay)anek,aHk,aynUvBaküxageRkam (a) entity (b) relationship (c) weak entity 2. GVIeTACa attribute? EckCab:unμanRbePT? cUrBnül; 3. GVIeTACa degree of relationship? EckCab:unμanRbePT? cUrBnül; 4. GVIeTACa cardinality ratio? EckCab:unμanRbePT? cUrBnül; 5. cUrBnül;BI Attribute inheritance?

6. cUrBnül;BI Generalization, Specification nig constraint elI supertype/subtype relationship?

7. cUrBnül;BICMhankñúgkarbMElg EER diagrams eTACa relations?

rrYss


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