Post on 04-Jun-2018
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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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RDBMS and Data Management/ Session 2/3 of 15
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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RDBMS and Data Management/ Session 2/4 of 15
Data Modeling
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RDBMS and Data Management/ Session 2/5 of 15
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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RDBMS and Data Management/ Session 2/6 of 15
Entity-Relationship (ER) model 1-4
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.
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Entity-Relationship (ER) model 2-4 Binary relationships: Cc mi quan h tn
tigiacc thcthcahai tpthcthkhcnhau.
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Entity-Relationship (ER) model 2-4 Ternary relationships: Mi quan h tn ti
gia ba thc th ca cc tp thc th khcnhau.
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Entity-Relationship (ER) model 3-4
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
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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
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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
Entity-Relationship (ER) model 4-4
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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
Entity-Relationship (ER) model 4-4
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RDBMS and Data Management/ Session 2/14 of 15
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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RDBMS and Data Management/ Session 2/15 of 15
Entity-Relationship Diagrams
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RDBMS and Data Management/ Session 2/16 of 15
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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RDBMS and Data Management/ Session 2/17 of 15
Customer
CusName
CusAddress
CusGender
CusPhone
CusEmail
CusUser
CusPass
SAnswer
Registerdate
Have
Classify
N
1
ClassID
ClassName
Description
CusID
Status
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RDBMS and Data Management/ Session 2/18 of 15
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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RDBMS and Data Management/ Session 2/19 of 15
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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RDBMS and Data Management/ Session 2/20 of 15
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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RDBMS and Data Management/ Session 2/21 of 15
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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RDBMS and Data Management/ Session 2/22 of 15
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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RDBMS and Data Management/ Session 2/23 of 15
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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RDBMS and Data Management/ Session 2/24 of 15
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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RDBMS and Data Management/ Session 2/25 of 15
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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RDBMS and Data Management/ Session 2/26 of 15
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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RDBMS and Data Management/ Session 2/27 of 15
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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RDBMS and Data Management/ Session 2/28 of 15
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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RDBMS and Data Management/ Session 2/29 of 15
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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RDBMS and Data Management/ Session 2/30 of 15
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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RDBMS and Data Management/ Session 2/31 of 15
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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RDBMS and Data Management/ Session 2/32 of 15
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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RDBMS and Data Management/ Session 2/33 of 15
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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RDBMS and Data Management/ Session 2/34 of 15
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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RDBMS and Data Management/ Session 2/35 of 15
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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RDBMS and Data Management/ Session 2/36 of 15
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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RDBMS and Data Management/ Session 2/37 of 15
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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RDBMS and Data Management/ Session 2/38 of 15
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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RDBMS and Data Management/ Session 2/39 of 15
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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RDBMS and Data Management/ Session 2/40 of 15
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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RDBMS and Data Management/ Session 2/41 of 15
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