Bài 2 1 Mô hình thực thể và chuẩn hóa.ppt

8/14/2019 Bi 2 1 M hnh thc th v chun ha.ppt

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Session 2

E-R (Entity Relationship)

Model and Normalization


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RDBMS and Data Management/ Session 2/2 of 15

Mc tiu bi hc

nh ngha v m t v m hnh ha d liu. Nhn bit v m t cc thnh phn m hnh

E-R

Nhn bit cc quan h gia cc thc th Gii thch v lc E-R, cc k hiu s dng

v v th hin cc quan h

M t v cc dng chun Cc ton t quan h


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Data Modeling

Data Model - l nhm cc cng c l thuyt m td liu, cc mi quan h v ng ngha ca chng.M hnh d liu cng bao gm cc rng buc ton

vn m d liu phi tun theo. M hnh ha d liu c th c chia lm ba bc

chnh sau:

Conceptual Data Modeling (khi nim) Logical Data Modeling

Physical Data Modeling


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Data Modeling


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Entity-Relationship (ER) model 1-4

Cc m hnh d liu c phn thnh ba nhm khc nhau Object-based logical models Record-based logical models Physical models

M hnh Entity-Relationship (E-R) thucvnhm utin. M hnhdatrn tngngin: D liuc thcnhnbitnhl ccitngtrong thgiithcgi l thcthv cc miquan htntigiachng.

M hnh E-R gm 5 thnh phn c bn: Entity (thc th) Relationship (quan h) Attributes (thuc tnh) Entity Set (tp thc th) Relationship Set (tp quan h)


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Accounts

Production

Human Resource

Logistics

works in

Employee

Entity Set

Employee

Entities

Department

Entity Set

Department

Entities

Relationship

Set


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Entity-Relationship (ER) model 2-4 Mi quan h gn kt mt hay nhiu thcthvinhau, cphn lm 3 loi:

Self relationships: Cc miquan hgiacc

thcthtrong cng tpthcth.



Entity-Relationship (ER) model 2-4 Binary relationships: Cc mi quan h tn

tigiacc thcthcahai tpthcthkhcnhau.



Entity-Relationship (ER) model 2-4 Ternary relationships: Mi quan h tn ti

gia ba thc th ca cc tp thc th khcnhau.




Cc mi quan h c th c phn loi theo yu t nh xnh sau: One-to-One: Loi nh x ny tn ti khi mt thc th ca mt

tp thc th c th gn kt ch vi mt thc th ca tp thc th

khc.

f

Vehicle

Entity Set

registration

Registration

Entity Set



Entity-Relationship (ER) model 3-4 Cc mi quan h c th c phn loi theo yu t nh xnh sau:

One-to-Many:Loinh xny tntikhi mtthcthcatpthcthc thcgnktvinhiuhnmtthcthcamttpthcthkhc.

f

Vehicle

Entity Set

f

f

Vehicle

Entity Set



Many-to-One: Loi nh x nay tn ti khi nhiu thc th ca mttp thc th kt hp vi mt thc th ca mt tp thc th khc.S kt hp ny c thc hin khng k thc th k sau kthp vi cc thc th khc hay khng.

f

h

f

Vehicle

Entity set

F

Location

Entity set




Many-to-Many: Loi nh x ny tn ti khi mt sthc th ca tp thc th c th kt hp vi mt sthc th ca tp thc th khc.

Account

Entity Set

Customer

Entity Set



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The E-R diagram is a graphical representationof the E-R model.

The symbols used for the various componentscan be seen in the following table:

Entity-Relationship Diagrams


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Entity-Relationship Diagrams


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Entity-Relationship Diagrams Steps to construct an E-R diagram are:

Tp hp tt c cc d liu cn c m hnh ha Xc nh d liu c th c m hnh ha nh cc thc th

thc t

Nhn ra cc thuc tnh cho mi thc th Phn loi cc tp thc th thnh cc tp thc th mnh hoc

yu Phn loi cc thuc tnh thc th thnh thuc tnh kha,

thuc tnh a tr, thuc tnh phc hp, thuc tnh dn xut,..v..v.

Nhn ra cc quan h gia cc thc th khc nhau. S dng cc k hiu v cc thc th, thuc tnh v cc mi

quan h ca chng. S dng cc k hiu thch hp trong khi

v cc thuc tnh.


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Customer

CusName

CusAddress

CusGender

CusPhone

CusEmail

CusUser

CusPass

SAnswer

Registerdate

Have

Classify

N

1

ClassID

ClassName

Description

CusID

Status


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Customer

CusName

CusAddress

CusGender

CusPhone

CusEmail

CusUser

CusPass

SAnswer

Registerdate

Order

1

Have

N

OrdID

OrderDate

ShipAddress

RequiredateDate

ShippedDate

ShipName

ShipPhone

StatusHave

Classify

N

1

ClassID

ClassName

Description

CusID

Status


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Normalization

Chun ha l qu trnh tch bng (phn r) thnh ccbng nh hn da vo cc ph thuc hm m khnglm mt thng tin.

Cc dng chun l cc ch dn thit k cc bngtrong CSDL.

Mc ch ca chun ha l loi b cc d tha v Yu cu v khng gian lu tr

Trnh cc li khi thao tc d liu (Insert, Delete,Update). Ch : chun ha lm tng thi gian truy vn.


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Cc dng chun(Normal forms)Bngvicc thuctnh atr

Chun 4(4NF)

Chun1(1NF)

Chun2(2NF)

ChunBoyceCodd

(BCNF)Chun 3(3NF)

Chun 5(5NF)

Loi b ccthuc tnh

a tr

Loi b ccph thucb phn

Loi b ccph thucbc cu

Ch cn cc phthuc X A

m X l kha

Loi b ccph thuc

a tr

Loi b ccph thuc

ni


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1NF (1) Ban u, Codd (1972) m t ba dng

chun (1NF, 2NF v 3NF), tt c da trn sph thuc gia cc thuc tnh ca quan h. First Normal Form - t c dng chun mt:

To ra cc bng ring bit cho mi nhm dliu lin quan.

Cc ct ca bng phi c cc gi tr nguyn t(atomic values)

Tt c cc thuc tnh kha phi c nhndng


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1NF (2)

MASV HOTEN IACHIMA

MONTENMON

TENGV PHONG IEM

A01 L Na 12 Thi HM01 CSDL Mai P13 8

M02 Anh 2 Lan P25 5

A03 Trn An 56 M My M01 CSDL Mai P13 6

A02 H Nam 34 CuG

M04 Ton 1 Nam P40 10

M02 Anh 2 Lan P25 7

M03 Vi m Chi P30 9

y khng phi l dng chun 1NF v thuc tnhMAMON,TENMON, TENGV, PHONG, DIEM c min gi tr"a tr".


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1NF (3)

Nhn xt:Hai bng quan h trn u cng qun l mt mng thng tin camt nhm i tng, c cu trc logic nh nhau nhng cu trc vt l khcnhau. Bng 1 quan h c 3 phn t, bng 2 quan h c 6 phn t. Chng tac th a mi quan h v dng 1NF.

MASV HOTEN IACHIMA

MONTENMON

TENGV PHONG IEM

A01 L Na 12 Thi H M01 CSDL Mai P13 8

A01 L Na 12 Thi H M02 Anh 2 Lan P25 5

A03Trn An

56 M My M01 CSDL Mai P13 6A02 H Nam 34 Cu G M04 Ton 1 Nam P40 10

A02 H Nam 34 Cu G M02 Anh 2 Lan P25 7

A02 H Nam 34 Cu G M03 Vi m Chi P30 9


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Dng chun 2 - 2NF (1)

Mtquan h 2NF nuquan h dng1NF v ccthuctnh khng kha phthuchon ton vo kha. BngR c cc phthuchm sau:

(1) Masv Hoten, Diachi

(2) Mamon Tenmon, Tengv, Phong (3) Masv, Mamon iem (4) Tengv Phong

Kha chnh: Masv, Mamon.

Tenmon, Hoten, Diachi l cc thuctnh khng kha vchphthucvo mtphncakha chat2 NF.


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MASV HOTEN IACHIMA

MONTENMON

TENGV PHONG IEM

A01 L Na 12 Thi H M01 CSDL Mai P13 8

A01 L Na 12 Thi H M02 Anh 2 Lan P25 5

A03 Trn An 56 M My M01 CSDL Mai P13 6

A02 H Nam 34 Cu G M04 Ton 1 Nam P40 10

A02 H Nam 34 Cu G M02 Anh 2 Lan P25 7

A02 H Nam34 Cu G

M03 Vi m Chi P30 9

MASV HOTEN IACHI

A01 L Na 12 Thi H

A03 Trn An 56 M My

A02 H Nam 34 Cu G

MAMON

TENMON

TENGV PHONG

M01 CSDL Mai P13

M02 Anh 2 Lan P25

M04 Ton 1 Nam P40

M03 Vi m Chi P30

MASVMA

MONIEM

A01 M01 8

A01 M02 5

A03 M01 6

A02 M04 10

A02 M02 7

A02 M03 9

R1 R3R2


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Dng chun 2 - 2NF (2)

Mtquan h dng2NF nuthamn 1 trong cc iukinsau Kha chnh chgm1 thuctnh. Bngkhng c cc thuctnh khng kha. Ttccc thuctnh khng kha phthuchon ton

vo tpcc thuctnh kha chnh. Gi

Chkimtra cc quan hc t2NF nuquan hc

kho chnh gm2 thuctnh trln. chuynquan htdng1NF sang dng2NF, ta

dng php chiu.


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Cc likhi dng2NF

LcR2(Mamon, Tenmon, Tengv, Phong) gmccphthuchm: (2) Mamon Tenmon, Tengv, Phong

(4) Tengv Phong

R2 t2NF. Vn

Liuc thphn phng cho 1 gio vin khi gio vinchadymn no?

Khi xa 1 mn hc, liuc lm mtthng tin vgiovin v phng?

Khi iphng cho 1 gio vin th phicpnhtlibao nhiu dng?


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Dngchun33NF

Mtquan h 3NF nuquan h 2NF v khng ccc phthucbccu. Mtlcquan hR 3NF nuvimiphthuc

X A ngtrong R v A X th hocX l kha baohm hocA l nguyn t.

A l thuctnh nguyn t(thuctnh kha)nuA lphntcamtkha caR (R c thc nhiukha),ngcliA l phi nguyn t.

Gista c quan hsvien(masv, hoten, khuvuc,congdiem)

Ta thynu1 thuctnh cxc nhbi1 thuctnh khngkho, n gil thuctnh bccu.Vycongdiemphthucvo khuvuc. chia thnh 2 quan h(3NF): svien(masv,hoten, khuvuc) v khu(khuvuc, congdiem)


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MASV HOTEN IACHI

A01 L Na 12 Thi H

A03 Trn An 56 M My

A02 H Nam 34 CuG

MA

MON

TEN

MONTENGV PHONG

M01 CSDL Mai P13

M02 Anh 2 Lan P25

M04 Ton 1 Nam P40

M03 Vi m Chi P30

MASVMA

MONIEM

A01 M01 8

A01 M02 5

A03 M01 6

A02 M04 10

A02 M02 7

A02 M03 9

R1 R3R2

MAMON

TENMON

M01 CSDL

M02 Anh 2

M04 Ton 1

M03 Vi m

TENGV PHONG

Mai P13

Lan P25

Nam P40

Chi P30

R2 R4

Mamon Tenmon, Tengv, PhongTengv Phong

MASV HOTEN IACHI

A01 L Na 12 Thi H

A03 Trn An 56 M MyA02 H Nam 34 Cu G

R1

MASVMA

MONIEM

A01 M01 8A01 M02 5

A03 M01 6

A02 M04 10

A02 M02 7

A02 M03 9

R3


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Relational Operators

M hnh quan h c da trn c s i squan h. i s quan h bao gm tphp ccphp ton hotngtrn cc quan h.

Mi ton tgi1 hoc2 quan hnhu vocan v ktququan hmil ura.

SELECT: This operator is used to extract data that

satisfies a given condition. The lowercase Greek lettersigma,,is used to denote selection.


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Select

Php ton ny rt ra cc bn ghi thamn iu kin no y.

Gi E l mt iu kin no bao

gm: Cc ton hng (hng, tn thuc tnh, vi

hng chui ta bao trong du nhy n

hoc kp) Cc quan h s hc (, , , ) Cc php ton logic: v, hoc v ph nh.


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Project PROJECT: This operator is used to project

certain details of a relational table. It onlydisplays the required details leaving outcertain columns. The PROJECT operator is

denoted by the Greek letter pi, . php chiu l ta nhn c mt quan h

t mt quan h cho bng cch b bti mt s thuc tnhno .

V d c quan h svien (masv, ho, ten,gtinh, nsinh, dchi, diemvt) ta ly ra bngsv(masv, ho, ten, diemvt)


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Product

PRODUCT: This operator is denoted byx. It helps combine information fromtwo relational tables.

Php nhn kt hp mi bn ghi cabng 1 vi tt c cc bn ghi ca bng2 tc l n to ra tt c cc kt hp c

th c gia cc bn ghi ca 2 bng


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Union (1)

UNION: The UNION operator collects datafrom different tables and presents a unifiedversion of the complete data. The union

operation is represented by the symbol,U. Cho R v S l hai quan h trn cng tp thuc

tnh U (ta gi cc quan h R v S l tngthch). Khi hp ca quan h R v S l mt

quan h H trn U, bao gm cc phn t thucR hoc thuc S. Hp ca R v S c k hiul R + S: R + S = {t | t R hoc t S}


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Union (2)

A B C A B C

a1 b1 c1 x1 y1 z1

a2 b2 c2 a1 b1 c1

a3 b3 c3 x2 y2 x2

A B C

a1 b1 c1

a2 b2 c2

a3 b3 c3

x1 y1 z1

x2 y2 z2

quan h H = R + S l:Cho hai quan h R v S nh sau:


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Intersection(1) INTERSECT:This operator generates datathat holds true in all the tables it is applied

on. It is based on the intersection settheory and is represented by the

symbol. Cho R v S l hai quan h trn cng tp

thuc tnh U. Khi giao ca quan h R vS l mt quan h G trn U, bao gm cc

phn t thuc R v thuc S. Giao ca R vS c k hiu l G=R*S:R*S = {t | t R v t S}


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Intersection (2)

A B C A B C

a1 b1 c1 x1 y1 z1

a2 b2 c2 a1 b1 c1

a3 b3 c3 x2 y2 x2

Cho hai quan h R v S nh sau: quan h G = R.S l:

A B C

a1 b1 c 1


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DIFFERENCE (1) DIFFERENCE:This operator, symbolized

as -. It generates data from differenttables, that holds true in one table and notthe other.

Hiu ca 2 quan h R v S trn cng tpthuc tnh U l mt quan h T trn U, baogm cc phn t thuc R v khng thuc

S. Hiu ca R v S c k hiu l R - S:R - S = {t | t R v t S}


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DIFFERENCE (2)

A B C A B C

a1 b1 c1 x1 y1 z1

a2 b2 c2 a1 b1 c1

a3 b3 c3 x2 y2 x2

Cho hai quan h R v S nh sau: quan h T = R-S l:

A B C

a2 b2 C2a3 b3 c3


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JOIN (1) JOIN: The join operation is anenhancement to the product operation. It

allows a selection to be performed on theproduct of tables.

Cho hai quan h R(U), S(V). Php kt nit nhin (Natural Join) ca hai quan h Rv S l quan h c k hiu l P = R|>


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Phnt

HOTEN GIOITINH

t1 Nguyn Vn Tun Nam

t2 Nguyn Huy Khi Nam

t3 L Th Hoa N

t4 L Th Hin N

t5 Phm Th o N

Phnt

HOTEN TUOI

t1 Nguyn Vn Tun 30

t2 Nguyn Huy Khi 32t3 L Th Hoa 25

t4 L Th Hin 28

t5 Phm Th o 22

Phn t HOTEN TUOI GIOITINH

t1 Nguyn Vn Tun 30 Nam

t2 Nguyn Huy Khi 32 Nam

t3 L Th Hoa 25 Nt4 L Th Hin 28 N

t5 Phm Th o 22 N


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DIVIDE DIVIDE:The division operation, denoted

by , is suited to queries that include thephrase for all.

Cc thuc tnh ca bng chia lun l tpcon ca bng b chia

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Bài 2 1 Mô hình thực thể và chuẩn hóa.ppt