overview of database system
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7/24/2019 Overview of Database System
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I-1 Copyright © Oracle Corporation, 2001. All rights reserved.
Database Management
System
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2Copyright © Oracle Corporation, 2001. All rights reserved.
An Overview of Database
System
Lesson 1
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What is Data?
•A collection of rawfacts, figres, !symbols" If a lot ofaccrate #ata is$rocesse# correctly,
we get valableinformation"
– %mbers
– Wor#s
– Images – &i#eo
– Son#s
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What is Data?
• (em$eratre, $ressre, rainfall an# win#s$ee# #ata can be $rocesse# to give aweather ma$"
• %ames an# a##ress of em$loyees is #atathat can be $rocesse# to give )ersonnelInformation"
• In a De$artment Store, the #ata abot
items sol#, their $rice, *antity an##e$artment names can be $rocesse# to
give management information"
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What is a #atabase?
A #atabase is a collection of#atainformation that is store# for as$ecific $r$ose an# organie# in amanner that allows its contents to beeasily accesse#, manage#, an# $#ate#"Althogh this #efinition incl#es store##ata collections sch as libraries, filecabinets, an# a##ress boo.s, when wetal. abot #atabases we almost invariablymean a collection of #ata that is store# ona com$ter"
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(wo basic categories of #atabase
• (he most commonly encontere# category is thetransactional database, se# to store #ynamic#ata, sch as inventory contents, which is
sb0ect to change on an ongoing basis" (heother category is the analytical database, se# tostore static #ata, sch as geogra$hical orchemical test reslts, which is rarely altere#"
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2am$le of #atabase St#ent Data
StudID FirstN LastN I Address City Telno CourseID
S12004 Jove Easley P 133 1st Street Ne !or" 4#$212$ %SCS1
S21&&& Jane S'it( E 434 4t( Street Los An)eles 4#21410 %SC*E3
S32000 +andy Doe * 143 2nd Street Detroit 321#444 %S%A2
S42001 ,eor)e -arley S ### 1st Street C(i.a)o 4##1//1 P+*,1
4iel#s
5ecor#s6ell
(able
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(here are five sim$le things that nee# to
be #one with the recor#s in the #atabase 8
• A## new recor#s 9create, ma.e, insert:
• Delete nwante# recor#s 9erase, $rge,remove:
• ;$#ate eisting recor#s 9alter, mo#ify,change:
• Sort the recor#s in any or#er 9reor#er, gro$:
• Search for recor#s that match a criteria9select, access:"
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2nter$rise
• A #atabase is a collection of $ersistent #atathat is se# by the a$$lication system ofsome given enter$rise" (he term
=enter$rise> here sim$ly a convenientgeneric term for any reasonably selfcontaine# commercial, scientific, technicalor other organiation" An enter$rise might
be a single in#ivi#al or similar large bo#y"
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@ere are some eam$les8
–A manfactring com$any
–A ban.
–A hos$ital
–A niversity
–A government #e$artment
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)ersistent Data
• Any enter$rise mst necessarilymaintain a lot of #ata abot itso$eration" Sch #ata is =$ersistent#ata>" An enter$rise wol# ty$icallyincl#e the following among their$ersistent #ata8
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)ersistent Data
–A )ro#ct #ata
–Accont #ata
–)atient #ata
–St#ent #ata
–)lanning #ata
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Database System?
• A Database System is s$ecial #ata$rocessing system or $art of the #ata$rocessing system which ai#s in thestorage, mani$lation, re$orting,management ! control of #ata"
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6om$onents of Database
System –Data an# Information
–Software
–@ar#ware
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6om$onents of Database
System-;sers
1" A$$lication $rogrammers
" 2n# sers
3" Database administrator (DBA) – Defining eternal schema
– Defining conce$tal schema
– Defining internal schema
– Biaison with sers
– Defining secrity an# integrity chec.s
– Defining bac.$ an# recovery $roce#res
– Monitoring $erformance an# changingre*irements
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Data
• is a re$resentation of facts, conce$ts, orinstrctions in a formatte# manner sitable forcommnication, inter$retation or $rocessing byhman beings or by atomate# means"
• Data8 5aw 4acts, in a form of tet, gra$hics,images, son# an# vi#eo segments that havemeaning in the serCs environment"2" Bist of em$loyees
ing
Allen
Ela.e
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@ierarchy of #ata
– Eits8 Einary #igits which vale of either or1, it is the smallest nit of #ata in acom$ter"
– Eyte8 A gro$ of that form information, a
se*ence of 7 bits" – 6haracter8 Al$hanmeric nit of #ata"
– 4iel#8 is the smallest logical fiel# of #ata"
– 5ecor#8 6ollection of relate# fiel#s"
– 4ile8 6ollection of relate# recor#s"
– Database8 6ollection of relate# #ata in a file"
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Information
• Data that have been $rocesse# in sch away as to increase the .nowle#ge of the$erson who ses the #ata"
Data in contet F e" )ayroll re$ort
Smmarie# #ata F e" Gra$h or 6hartre$ort
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Software
• DES Sot!are is the $rogram that #efinesan# manages a #atabase, stores the #ata,s$$orts a *ery langage, $ro#ces
re$orts, an# creates #ata entry screens"
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@ar#ware
• DES "ard!are is the $hysical #evice which iscom$ose# of the secon#ary storage volmes Fmostly magnetic an# com$act #is. F that are se#to hol# the store# #ata, together with the
associate# IO #evices 9#is. #rives, etc":, #evicecontrollers, IO channels, an# so forth" Another oneis the har#ware $rocessor9s: associate# with mainmemory that are se# to s$$ort the eection ofthe #atabase system software"
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DES ;sers
– System analyst re*irement analysis – Database #esigner generate #ata mo#el
– A$$lication $rogrammer im$lement thetransactions an# ser interface
– )ro0ect manager monitor the $rogress of theim$lementation
– 2n# ser eecte transactions
– Database a#ministrator tne the #atabase
$erformance
– System a#ministrator monitor the system$erformance an# $#ate softwarehar#ware whennecessary
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4eatres of a DES
– A #ata mo#elling $ara#igm 5elational DataMo#el
– Mathematical fon#ations of #atabase #esign
– @igh level $rogramming langage SHB
– Many im$lementations
– Other #ata mo#els eist, an# are being #evelo$e#
– %etwor., ob0ect-oriente#, MB
– DEMS stores a rich set of #ata ty$es images,tet, a#io an# vi#eo, geogra$hic #ata
– DEMS $rovi#es online access re*ests are$rocesse# at the time they are initiate#
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4eatres of a DES
– DEMS allows concrrent access mlti$le
transactions may be $rocessing at the same time – DEMS may involve #istribte# #ata a single
transaction may nee# to access mlti$lenetwor.e# sorces
– DEMS may involve #istribte# $rocessingcom$le o$erations are not necessarily carrie#ot where the #ata is store#
– DEMS a$$lication may be heterogeneos a
single a$$lication may s$an mlti$le DEMSim$lementationssystems
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DES 4nctional Strctre
• (he =#ront$%nd>
– ;ser-written a$$lications
– embe##e# *eries
– re*ires DEMS A)I to lin. nativelangage with DEMS langage
– DEMS a$$lications
– #irect access to DEMS *ery $rocessor
– re$ort writers
– natral-langage *ery $re-$rocessors
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DES 4nctional Strctre
• (he =&ac'$%nd>
– (he DEMS itself
– *ery $rocessor
– secrity, concrrency, integrity
– #ata #efinitions, view #efinitions
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Sam$le DES?
– S$$ose we are constrcting a =St#ent5egistration System> with the followingfnctionalities for st#ents an# faclty8
– ;sers athenticate themselves
– 5egister for corses offere# net semester
– Obtain re$orts on $articlar st#entCs stats
– Maintain information abot st#ents an#corses
– 2nter final gra#es for corses that a st#enthas com$lete#
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2voltion of the DES
• #LA( #)L% *atabases
• ")%+A+C")CAL *atabases
• %(-O+ *atabases• +%LA()OAL *atabases
• O&/%C( O+)%(%* *atabases
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2voltion in DEMS
#)L% ")%+A+C")CAL %(-O+ +%LA()OAL O&/%C( O+)%(%*
AL)CA()O
*A(A
DBMS History
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6ontining (echnical 2voltion
– 103s4 #ile processing 5CO&OL6
– 1703s4 +elational *atabases on )&8 8ainra9es5*&2 and S:L6
– 1;03s4 +el *&8S or 8icros 5+$&AS%, *&AS% )),
etc...6
– 103s4 <ative= Client$Server, Ob>ect$Orientation5CO+&A, O+ACL% o!er Ob>ects6 Co99on Ob>ect+e?@est &ro'er Architect@re "
– 20003s4 /ava$driven <on native= Client Server58any prod@cts in develop9ent6
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2am$les of DEMS
A$$lications
– Oracle
– )ngres
– )nor9iB 5niB6
– 8ys?l
– *&2, S:LD*S 5)&86
– Access 58icrosot6
– S:L Server 58icrosot E6
– 8any older 5#oc@s, )8S, ...6
– 8any li9ited C 5d&ase, aradoB, F6
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A#vantages of
Database A$$roach
– 8ini9al data red@ndancy.
– *ata consistency.
– )ntegration o data.
– Sharing o data. – #ast, better and standard data access
– %norce9ent o standards.
– (ransaction s@pport
– %ase o application develop9ent and 9aintenance.
– nior9 sec@rity, privacy and integrity.
– *ata and progra9 independence.
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Drawbac.s of ol# 4ile metho#s
– ncontrolled *@plication
– -astes space
– "ard to @pdate all iles
– )nconsistent data
– )nleBibility
– "ard to change data
– "ard to change progra9s
– Li9ited data sharing
– oor enorce9ent o standards
– oor progra99er prod@ctivity
– %Bcessive progra9 9aintenance
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;se a DEMS when this
is im$ortant• $ersistent storage of #ata
• centralie# control of #ata
• control of re#n#ancy
• control of consistency an#integrity
• mlti$le ser s$$ort
• sharing of #ata
• #ata #ocmentation
• #ata in#e$en#ence
• control of access an#secrity
• bac.$ an# recovery
Do not se a DEMS
when the initial invest9ent in
hard!are, sot!are, and trainingis too high
the generality a *&8S provides
is not needed
the overhead or sec@rity,
conc@rrency control, and
recovery is too high
data and applications are si9ple
and stable
real$ti9e re?@ire9ents cannot be
9et by it
9@ltiple @ser access is not
needed