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1 Ihtroduction toDatabases
41 Basic Concepls gf databases
Ahat is Database?
Adatabase is an arganixed callecion of sucred
data that s stored elestonicallq and can be. gcessed rnangged,
gnd manipulatcd efficients-lE seves asa repa_itors for
stoxioq ahd managing data for vaxioLS. apglibatians.
In daBabaee,data is organizes into tablesie
relahions Each table onsists o rous (recmrcds) and columms
(attibutes) that repiesent ditferent piaces of informatian
Daa:
Daka is a aollecian of kacs and fiqures hat can be
pYocessed to pioduce inkomaion.
Database. Manaqgnent Sastem(DaMs)
Database. manggement sem ia a callection of
intcr-related data and programs to acess those data
The challengas for data managemen:
Traditiana Alk-based data manaqement
sufFer fiom sexeral chalengas, such as data redundand
inonsictena and isalatian
Data Redundansy: n file- based syslems, data ks aEBen
duplíated malipe fies sr appliationa Thia
elAssMate
Data
Pege
duplicctian. can lead to cata inconsistenxy.s changsmadeto
one copy of the data migtt not be efleckd in ather opies
Data _Inconsis ency: When the stune data js siored in different
Files or formats, it cgn lead to inconsistencies inthe yalues
and meanings of data
Data isolation: File-based suskems are affen isolaBed fram eact
oher, making it difPicut shae data acusss
appliations
12 Oatabase Maragenent Syskm Achitechare
The D8I1S desiqp depernds upon its archiBecture. The
bosis client /servers archtcckure is ased to deal oith alage
bumber oF PCs, weh servers, databaso serers and oher
Components hat are conneched with networks.
The client/server archiBecture. cansists o many s and a
wotkstakon which dre connected via the netork
DBMS_ architechure. depends upan houy uSers are cannected
to the catabase. to get heit request done
ypes of DBMS Architecture
DBMS
Architeure,
1-tier 2-tier 3-tier
Architechure) Architechure Architectie
sssmte
Dete
Dakabase archidecture_ can be seen_ as. a sinale tier on mulki- ien
But logjcaly.dakabase. anchilecture is af wo types like
Q-tier architecure. and 3-ier auchitecture
-Ter Architeckure
Th this aichitecture, the database is diecs available
to the ser-H nedns the user aun directls sit an the DBIIS
and uses t
Any changes done here will directs be cone. on the database
ksel:. Adoesnt provide a hands tosl ennds user
-Tier ArchiBecure. :
The 2- Tier Architecture is same. gs basic cient
server n he tuo-tier archiBecre applications on he client
end can direchs communicate. with he clatabaLse at the
senver sidle. For this interaction, AP's_ like. s0DBL, TDBC are uæ
LDatabase systen SPYVeY
Aplication
client
User
fiq: 2-ter guchilecture.
classMate
Dele
Psce
3-Ter Architeckure :
The 3- tier qrchitechure contains Jajer betuween he.
dient and seYer. In this _architecture,client cant directy
Communicate with senver
Database
SeLVer
APPlication Server)
APelicaton client dient.
User
fig 5-tier Architectue
13 Data Madels (relaiong, hieraxchical hehibrk, eo)
Data model s the. modelig oF the cata desciption
data semantics, and consiscncy conshsains oF the. data. it
psavides he onceptual tools For describing the design oF a
database each leyel oF daBa cbstcion.
Thereforethere are.
llaig foua data macels. usad or sunderaBanai_ the shcue
LoF the database
Data Models
ORelatoral QSemistruchred Enhty.
EntiBy objec
daBa model doBa model Rekationship based
data mode modet
elassmate
Date
ece
)Relatonal dua Model:
his yped Mmodel desiqns the data in the fome
oF TowS,and colums e table. also_ called as_relatians
Reltional mocdpluaes tables for representing data and in
bekaen relaionships
1AEnty- Relationship Data Model
An ER 'model is the oaical reoresentation o
Ldat as obiecs and elationships among them. These object
ahe knoun gs enfities, and relationship is qn qssociahon
amongq these entities Jhis_model was desianesl by peBej
Land publiched in LaZ6 Bapers. T! was wjda use
chen and published in widels
in database. dosigning I976 papera
l) dbiject based cata NModel:
An extensian oF the ER model with notions a
nchiors, encapsukaton and ahject identity,ao wel This
model auppatts a rich tpe siskem that incldes stuct
ured and collechion ypes Thus, in Iggo's yarious
Ldatabase. sustcms folouing he chiect-aHiented appimach.
were developed
4 Semistaucured data Mode:
This type gt data Motel is aterer fiom the.
Gother hre daa ilel! Çeplained akae The sem/-stuct
Lured data model allouns te data peafittons_ at places
uhere the indivducl data items o he same tpe may
Lhave ditkerent attibutes sets. The Exdensible Maukup
anquagealso known as XL d Was a g designed
semiotuchure
t iepkseni the
elasct
14 Aduantagqes and digad vantaqs of ucing DaMs
Advarhaqss g woing DRTIS:
1DaB,imegity: Databases enlorce dala inlegrts constaints, such
ds primnarg' kens , foreign kes aind unique constraints.,to
maintain acurate and consistent data This ensures that
data is reliable. and fiee ton inconsishcncies:
2Daia Sectatky: Daabasesoffr various seuriky feaares ,suh
Las acess contal,cunhentioion, and encryphion,t protect
sensitive informaton fom_unauthoxized_ qcess and data
breaches
5 Data shain: Databases enables.maltiple users and appl
to access and modiky daBa concurteny This facillitates
ollaborahian and foloWS for Cettalized daa'manggenehnt,
leading to beter data shaing actossgn argunization:
4DaBa Independence Databases provide clata independence,
epratinq t physical storaqe dE data from Ahe Joqical view:
s ahstachion allous Changes to be made to the dakabase.
sBucture athout affectin the applikaions tat use the.
dcta, making mainkainante and scalabilkts easiex
5Data Backup and Recovexs : Databases offer mechanisms for.
that data
vEqular data'beckups and vestore poiaks, ensuing_
an be reoreed in case. of taware failures, hunan eoxS..
atages uing DBrMs
Dsadantsges
Cost Seting up and maitainin a database,
gusBam qan be
expensive, 2speiallyfr small- scale. applications Costs. incke
harduzre.,sothaare licences tainin ane ongpinq maiatainae.
elassaae
ate
s onmtly Degying and nanagjng databasas regure speaia
xed kroalede and chils. he omplexty of database Syskns
|may be challenging for non- orperts to understand f maitain
3Single poitt o ailure:Adatabase failure can aflsct the
entire system 1f proper backup and iecovery mechanisms ge
not in place, data' loss Can ocur, leading to aiqnticant dis
uptions in operatians
4Scalabiliy challenges: As daBa valumes grou, scaling databases
to handle. increased loads may become.complex and costi
Ensuning high pertamance. under heavs loads oan be.a challenge :
