MELJUN CORTES MANUAL DataBase System CSCI12

8/13/2019 MELJUN CORTES MANUAL DataBase System CSCI12

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CSCI12 Instructional Manual

2nd trimester, SY 2007-2008Prepared by: ELJUN P. CORTES

PRELIM PERIOD

Lecture no. 1: DATABASE SYSTEMS

1.1 Introduction to Database Systems

Database DB!- An integrated collection of related data

By relateddata we mean tat te data represents logically coerent facts abo!t some

aspects of te real world tat are re"!ired by an application

Uni"erse o# discourse or mini$%or&d- #e part of te real world tat a database is

designed to model witin a comp!ter

By integratedwe mean tat te data for m!ltiple applications is stored togeter

and manip!lated in a uniform wayon a secondary storage s!c as a magnetic or an optical

dis$% #e primary goal of integration is to s!pport information saring across m!ltiple

applications%

a Database System consists of &' an application specific database, 2' te (B)S tat

maintains tat database, and *' te application software tat manip!lates te database

College of Computer Studies Prepared by: ELJUN P.CORTES1


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Database Systems and Database Mana'ement Systems

A Database Mana'ement System DBMS) is a collection of programs tat controls a

database% Specifically, it pro+ides !s wit an interface to create, maintain, and manip!late

m!ltiple databases

(B)S is a general-p!rpose software system tat we can !se not only to create and

maintain m!ltiple databases b!t also to implement database systems for different applications as

well%

As opposed to a (B)S, wic is general-p!rpose, a database system is de+eloped to

s!pport te operations of a specific organiation or a specific set of applications%

T(E DATABASE APPROA)(ES

.ays of /andling (atabases'

&% Manua& * man!al manip!lation of data

E+.)an!al card catalog

2% )om,uteri-ed electronic data andling

Traditiona& i&e Processin' System TPS!

Database Mana'ement System DBMS!

DBMS "s TPS

TPS $ application programs directlyfilenames and data definitions are embedded in

eac program%'

-data are integrated in a single, sared data file, all application programs tat

sare te data file m!st be aware of all te data in te file, incl!ding tose data

items tat tey do not ma$e !se of or need to $now

- #e problem gets worse wen a new field is added to a data file

Disad"anta'es o# TPS

&% 1ncontrolled ed!ndancy

2% 3nconsistent (ata

*% 3nfle4ibility

5% 6imited (ata Saring



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% Poor nforcement of Standards

9% 6ow Programmer Prod!cti+ity

7% 4cessi+e Program )aintenance

DBMS $ stores te str!ct!re of te data as part of te description of te database in te

system catalog, separately from te application programs

)/aracteristics o# DBMS

Data Abstraction

(B)Ss allow data to be str!ct!red in ways tat ma$e it more !nderstandable and

meaningf!l to te applications tan te ways data are pysically stored on dis$s% #ey pro+ide

!sers wit ig-le+el, concept!al

re+arwwwappscon+ersiontmpscratc;9&ect-oriented (B)Ss, to gi+e two e4amples=wile tey

ide storage details tat are not of interest to most database !sers%

program-data independence - te pysical organiation of data can be canged wito!t

affecting te application programs

program-operation independence- te implementation of abstract operations can be

canged wito!t affecting te code of te application programs, - as long as teir calling interface

stays te same

Data abstractionand, in partic!lar, data inde,endenceis wat facilitates data saring

and integration% #is is te main ad+antage of (B)S against #raditional ?ile processing wose

application programs depend on te low-le+el str!ct!re of te data or storage organiation, eac

program stores its data in a separate data file

Re&iabi&ity

(B)Ss pro+ide ig reliability by &' enforcing integrity constraints and 2' ens!ring data

consistencydespite ardware or software fail!res%



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Inte'rity constraints reflect te meaning or, te semantics' of te data and of te

application e4% (ata type'

Constraints conditions, restrictions

Data consistencytat is, interr!pted !pdate operations do not corr!pt te database wit

+al!es tat +iolate te integrity constraints and no data in te database is lost%

After a fail!re, a (B)S a!tomatically reco+ers, restoring te database to te

consistent state in wic it e4isted >!st prior to te interr!ption% #is consistent state is

constr!cted as follows% (!ring reco+ery, a (B)S ro&&s bac0all interr!pted transactions,

obliterating teir !pdates from te database, and re-e4ec!tes s!ccessf!lly terminated

transactions as necessary, restoring teir !pdates in te database

E##iciency

(B)Ss s!pport bot efficient space !tiliation and efficient access to data% By ma$ing !se of te

data description in te catalog, (B)Ss are able to minimie data red!ndancy, wic in t!rn sa+es

botspace,by storing eac data item only once, andprocessing time,by eliminating te need of

m!ltiple !pdates to $eep te replicas consistent and !p-to-date%

(B)Ss enance te performance of "!eries by means of optimiations and te !se of access

metods to data based on teir +al!es% @ptimiations simplify te "!eries so tat tey can e4ec!te

faster,

and access metods allow direct access to locations were rele+ant data are stored, in a way

similar to te access pro+ided by te inde4 in te bac$ of a boo$%

(B)Ss decrease response time of transactions by allowing m!ltiple !sers to access te

database conc!rrently

1. Re&ationa& Databases

Re&ationa& Database Sc/ema

A relational database schema is a set of table scemas and a set of integrity constraints%

3ntegrity constraints can be sorted into two $inds:

str!ct!ral model-specific' integrity constraints tat are imposed by te model as

disc!ssed below, and

semantic application-specific' integrity constraints imposed by te application, s!c as

te constraint, for e4ample, tat te balance of a sa+ings acco!nt cannot be negati+e%



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2eys $ eys are col!mns wose +al!es are s!fficient to !ni"!ely identify a row

TYPES O 2EYS

&% Primary ey !ni"!ely identifies a record

2% Secondary ey !sed to access a gro!p of records wit common attrib!tes

*% Alternate ey candidate to be Primary ey

5% omposite ey composed of two or more col!mns to access a !ni"!e record

% ?oreign ey - a non- key attributeordinary col!mn ' in one table, b!t a primary $ey

in anoter%

- establises associationrelationsips' among tables witin one database

in a relational database scema'

DDL Data De#inition Lan'ua'e!

#e command to create a table in SC6 is te A# #AB6 command% SC6

s!pports all te basic data types fo!nd in most programming lang!ages: integer, float,

caracter, and caracter string% SC6 commands are not case sensiti+e%

A# #AB6 ))B

)emDo integer5',

(ri+er6ic integer,

?name car&0',

)3 car,

6name car&',

PoneD!mber car&5',

P3)AY Y )emDo',

1D3C1 (ri+er6ic'

'E

#e primary $ey is specified !sing te P3)AY Y directi+e, alternate $eys !sing te

UNIQUEdirecti+e



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DML Data Mani,u&ation Lana'ua'e!

3,date O,erations

elational ()6 allows !s to insertand deleterows in a table as well as to update te

+al!es of one or more col!mns in a row%

3n SC6, only one row can be inserted at a time, by specifying te +al!es of eac col!mn,

as in te following e4ample:

3DS# 3D#@ ))B

VALUES (101, 6876588, 'Susan', W, 'Jones', '4123768888'!"

#is statement inserts a new row for S!san .% Fones in te ))B table% 3n SC6,

strings are enclosed witin single "!otes%

Delete and updatecan be applied to m!ltiple rows tat satisfy a selection condition% 3n SC6, a

selection condition in a deletion is specified by a ./ cla!se% 3n te simplest case, a row is

selected by specifying te +al!e of its primary $ey% ?or e4ample, te statement

(6# ?@) ))B

./ )emDo G &02E

deletes te row wit member n!mber &02 from te ))B table% #e following statement

canges te middle initial of te member &0& in te ))B table%

1P(A# )ember

S# )3 G S

./ )emDo G &0&E

An !pdate operation s!cceeds if it does not +iolate any integrity constraints% ?or e4ample,

an insert operation will not s!cceed if it attempts to insert a row wose $eys, primary and

alternate, conflict wit e4isting $eys% #at is, if te row were to be inserted, te property tat $eys

so!ld be !ni"!e wo!ld be +iolated% @n te oter and, deleting a row ne+er +iolates a $ey

constraint, !nless te deleted row is referenced by a foreign $ey% 3n tat case, deleting a row

migt +iolate a referential integrity constraint



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TOOLS OR 43ERIES

1! 4BE 4uery By E+am,&e!

C!ery By 4ample CB' is anoter +is!al "!ery lang!age de+eloped by 3B) HIloof,

&


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Se&ection in 4BE

CB2: etrie+e all members wose first name is Fon%

))B N)emDoN (ri+er6icN ?nameN )3N 6nameN AddressN PoneD!mberN

P% Fon

By placing P% !nder te table name, tis will retrie+e and display te data in all te

col!mns%

CB*: etrie+e te name and member n!mber of all te members wose member

n!mber is greater tan &00%

))B N)emDo N (ri+er6icN ?nameN )3N 6nameN AddressN PoneD!mberN

O&00 P% P%

omparison wit constant +al!e in te abo+e e4ample te constant +al!e is &00' is

placed in te appropriate col!mn% #e res!lting table will a+e te following col!mns:

es!ltN )emDo N ?name N 6name N

3n CB, a dis>!nction @' is e4pressed by !sing different e4amples in different rows of

te s$eleton%

CB5: etrie+e te name and member n!mber of all te members wose first name is Fon or

S!san%

))B N)emDoN (ri+er6icN ?nameN )3N 6nameN AddressN PoneD!mberN

P% P%Fon P%

P% P%S!san P%

A con>!nction AD(', on te oter and, is e4pressed in te same row%

CB: etrie+e te name and member n!mber of all te members wose first name is S!san and

wose member n!mber is greater tan &00%



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P%O&00 P%S!san P%

3f te con>!nction is a condition in+ol+ing a single col!mn, te condition can be specified

!sing te AD( operator, as in SC6% ?or e4ample, if te )emDo so!ld be greater tan &00 and

less tan &0, tis is specified !nder te )emDo col!mn as: ;4 O &00 ' AD( ;4 &0 '

6oin in 4BE

Foins can be e4pressed by !sing common e4ample +ariables in m!ltiple tables in te

col!mns to be >oined%

CB9: 6ist te member n!mber and last name of all te members wo c!rrently a+e a borrowed

boo$%


P%;>oin P%

B@@NBoo$;idNallD!mberNditionNBorrower)emDoNBorrow(!e(ateN

;>oin

#o e4press m!ltiple >oins yo! can !se m!ltiple e4ample +ariables at te same time%

SEAT7OR2:

&%.at is a elational (atabaseQ

2%n!merate te different types of eys and gi+e an e4ample

C13I R &

Lecture no. : )om,&ete S4L

.1 S4L

Str!ct!red C!ery 6ang!age

SC6 is te de-facto standard "!ery lang!age for relational (B)S%

College of Computer Studies Prepared by: ELJUN P.CORTES#


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- is a compreensi+e lang!age pro+iding statements for bot data definition and data

manip!lation%

SC6 ((6 (ata (efinition 6ang!age'

- Pro+ides basic commands for defining te concept!al scema of a database%

SC6 Pro+ides * D!meric data types:

&%' 4act D!mber #ese are integers or wole n!mbers wic maybe positi+e or

negati+e or ero%

SC6 S!pport 2 integer types:

&%' 3nteger 3D#'

2%' S)A663D#

2%' Appro4imate n!mber tese are n!mbers tat cannot be represented e4actly, s!c as

real n!mbers and fractional types%

*%' ?ormatted D!mber teses are n!mbers stored in decimal notation%

?ormatted n!mbers can be defined !sing te ff:

&%' (ecimal i>'

2%' ( i>'

*%' D!meric i>'

.ere: 3 G is te precision on te total n!mber of digits e4cl!ding decimal point%

F G is te scale, on te n!mber of fractional digits%

(efa!lt scale is ero 0'

Synta+ in creatin' a database name in S4L 4uery ana&y-er

&%' A# (A#ABAS (A#ABAS DA)O

1S (A#ABAS DA)O

2%' A# (A#ABAS DA)O

@D

DA) G (A#A ?36 DA) ?36DA) G 6@A#3@D @?%)(?OT'

*%' A# #AB6 #B6D)O

?6(D)O (A#A#YPO6DU#/O' P3)AY Y,



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?6(D)O (A#A#YPO6DU#/O' D166D@# D166O

'E

5%' 3DS# H3D#@J tableO Hcol!mn;list'J

VA61S data;+al!es'

%' S6# W ?@) #AB6DA)O

SPE)II) RELATIO8AL OPERATIO8S

&%' Pro>ection @peration X'

- Selects te attrib!tes or an attrib!te list from a table r, wile discarding te +est%

2%' Selection @peration '

-

Selects some rows in attrib!te r tat satisfy a selection condition alias predicate'%

*%' Foin @peration

- ombines two tables in one, tere by allowing !s to obtain more information%

SEAT7OR2:

&%' .at is SC6 and itZs capabilitiesQ

2%' reate a (atabase, 3nsert +al!es and +iew te data inserted%

43I9

PRELIM E;AMI8ATIO8

MIDTERM PERIOD

Lecture no. 1: DATABASE DESI


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- tis personnel will increase or may increase prod!cti+ity

so!ld not minimie s$ills '

. 8eed to e+,&icit bac0 * u,

- pro+ide bac$ !p copies of data beca!se :

a% it is elpf!l in restoring damaged data files

b% pro+ides +alidity cec$s on cr!cial data

=. Inter#erence %it/ s/ared data

- conc!rrent access to sared data +ia se+eral application program

problems

a% wen 2 conc!rrent !sers bot want to cange te same or related data

inacc!rate res!lts can occ!r if access to data is not properly

syncronied%

b% .en data are !sed e4cl!si+ely for !pdating, different !sers can obtain

control of different segments of te database to loc$ !p any !se of

te data%

Or'ani-ationa& )on#&ict

- a sared database re"!ires a consens!s of data definition

a% conflicts on ow to define data lengt and coding rigts to !pdate

sared data and associated iss!es%

TYPES O DATABASE

1. O,erationa& Database

- contains b!siness transaction and istory of daily b!siness

acti+ities

- !sed to s!pport te on going daily acti+ities of te organiation

- !se on te #ransaction Processing System 4% !stomers

orders, p!rcases, acco!nting, sipments and payments



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. Mana'eria& Database

- !sed by middle managers for planning control, s!mmaries of

operational database

- s!mmary of operation

- !se on )anagement 3nformation System

=. Strate'ic Database

- !sed by senior managers to de+elop corporate strategies and see$

competiti+e ad+antage

- contains information on competitors to economic factors as well

as corporate information

- !sed on (ecision S!pport System

IRO8ME8T


(A#A A()3D3S#A#@S SYS#) (V6@PS D( 1SS

Application!ser interfaceAS tools


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1. )ASE Too&s

- omp!ter Aided Software ngineering AS ' tools

- A!tomated tools !sed to design databases and application program

. Re,ository

- centralied $nowledge base containing all data definitions, screen

and report formats and definitions of oter organiations and

system components containing definitions of data format

=. DBMS - commercial software system !sed to pro+ide access to te

database and repository

?. Database

- an integrated collection of data, organied to meet te information

needs of m!ltiple !sers in an organiation

- contains occ!rrences of data +al!e itself

@. A,,&ication Pro'rams

- comp!ter programs are !sed to create and maintain te database

and pro+ide information to !sers

. 3ser Inter#ace

- lang!ages, men! and oter facilities interacted by te !sers front

and s!pport

- !se of men! dri+en system, mo!se and +oice recognition system

to promote end !ser comp!ting !ser wo are not e4perts, can

define teir own report, displays and application


epository(B)S

(atabase


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. Data Administrators

- persons wo are responsible for designing databases and for

de+eloping policies regarding databases sec!rity and integrity

- tey !se AS tools to impro+e te prod!cti+ity of databases

planning and design%

C. System De"e&o,ers

- persons s!c as system analysts and programmers wo design

new application programs%

- #ey !se AS tools for system re"!irement, analysis and

program design%

. End 3sers

- persons tro!g te organiation wo adds, edits, delete and

recei+e information

- encoders

Lecture no. : E8TITY * RELATIO8S(IP MODELS

2%& Entity * Re&ations/i, mode&s

E8TITY * RELATIO8S(IP MODELS

elationsip between two or more entities%

)ATE


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S#1( R )P6@Y R

4ample of data items tat as - meaningf!l association

S#1( R S#1(D)

#ypes of Association

1. One $ association - means tat at any point in time, a gi+en +al!e of A

as one and only one +al!e of A, ten te +al!e of B is implicitly $nown% 3mplicitly

$nown means tat it can be !nderstood to!g not plainly e4pressed% .e represent a

one association wit a single eaded arrow%

A B

4%

)P6@Y A((SS

2% )any association - means tat at any point, a gi+en +al!e of A as one or

many +al!es of B associated wit it% .e represent a many association wit a do!ble

eaded arrow%

4% A B

S#1( R S1BF#S

M3LTI>AL3ED ATTRIB3TE - occ!rs potentially m!ltiple times for eac item

of A

*% onditional Association - wit tis, for a gi+en +al!e of data item A tere

are two possibilities: eiter tere is no +al!e of data item B or tere is one or

many ' +al!e s' of data item B% A conditional association is represented by a

ero recorded on te arrow near te conditional item%

A B

4% onditional item



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B( PA#3D#

A(3DA63#Y - term !sed by te analysts tat is represented by te arrow

eads and eros on te arrows wic can be to!gt of as a+ing minim!m and

ma4im!m +al!es%

Re"erse Association

3f tere is an association from data item A to data item B, tere is also

a re+erse association from B to A%

Ty,es o# Re"erse Association

&% @ne to one association

)eans tat at any point in time, eac +al!e of data item A is associated

wit ero or e4actly one of data item B% on+ersely, eac +al!e of B is associated wit

one +al!e of A%

A B

4%

S#1( R S#1(D)

2% @ne to many association

)eans tat at any point in time, eac +al!e of data item A is

associated wit ero, one or many +al!es of data item B% /owe+er, eac +al!e

of B is associated wit e4actly one +al!e of A% #e mapping from B to A issaid to be many - to one, since tere may be many +al!es of B associated wit

one +al!e of A%

A B

4%

S#1( R MA)

*% )any - to many association

)eans tat at any point in time, eac +al!e of data item A is

associated wit ero, or one or many +al!es of data item B% Also eac +al!e of

B is associated wit ero, or one or many +al!es of A%

A B

4%

S#1( R @1S



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33% ASS@3A#3@D B#.D @(S

Sows te relationsip between records%

rowZs ?oot - !sed to disting!is one and many associations between entities

and records%

rowZs ?oot Dotation - !sed to represent te association between records%

#ypes of Association

&% @ne Association - no crowZs foot one - to one '

/1SBAD( S#1(D#

4%

.3? UA(

2% )any Association - represented by a crowZs foot

)P6@Y S#1(D#

4%

BD?33AY @1S

DATA MODELS

epresentation of te data abo!t entities, e+ents, acti+ities and teir associations witin

te organiations%

)ATE


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properties and str!ct!res and andling ob>ect of different types images, +oice print, as

well as te4t and data ' are incl!ded in te S() and oter semantically ric data models%

II. RELATIO8AL DATA MODEL

#e relational data model !ses te concept of a relation to represent wat we a+e

pre+io!sly called a file tat is a relation represents an entity class% A relation is +iewed

as a two dimensional table%

#e coice of many database b!ilders and !sers is te relational data model% 3t is

different from oter models not only from te arcitect!re b!t also in te following ways

:

1. Im,&ementation Inde,endence - it logically represents all relationsips implicitly

and ence, one does not $now wat associations are or not pysically represented by an

efficient metod% elational sares tis property wit (%

. Termino&o'y - it !ses its own terminology, most of wic as e"!i+alent terms in

oter data models%

=. Lo'ica& 2ey Pointers - it !ses primary and secondary $eys in records to represent

te association between 2 records, wereas ( !ses arc between entity bo4es%

?. 8orma&i-ation T/eory - properties of database tat ma$e it free of certain

maintenance problems a+e been de+eloped witin te conte4t of te relational data

model alto!g tis properties can also be designed into an ( or a networ$ data

model '%

College of Computer Studies Prepared by: ELJUN P.CORTES1#


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@. (i'/ Le"e& Pro'rammin' Lan'ua'es - P% 6% a+e been de+eloped specifically to

access database defined +ia te relational data modelE tese lang!ages permit data to be

manip!lated as gro!ps of files tan proced!rally one record at a time%

III. (IERAR)(I)AL DATA MODEL

@rganiations are !s!ally +iewed as a ierarcy oppositions and a!tority% omp!ter

programs can be +iewed as ierarcy of control and operating mod!lesE and +ario!s

ta4onomies of animals and plants +iew elements in a ierarcical sets of relationsip%

#e ierarcical data model represents data as a set of nested one to many relationsips,

te ierarcical data model is !sed e4cl!si+ely wit ierarcical database management

systemsE since s!c systems are in general, being pased o!t%

I>. 8ET7OR2 DATA MODEL

#e networ$ data model permits as m!c or as little str!ct!re as is desired% .e can

e+en create a ierarcy a special of a networ$ ' if tat is wat is needed% As te

ierarcical data model, if a certain relationsip is not e4plicitly incl!ded in te database

definition, ten it cannot be !sed by a (B)S in processing a database%

>. E8TITY RELATIO8S(IP DATA MODEL ER * DIAects

called entities and relationsips among entities ob>ects% 3t is a grapical notation tat

!ses special symbols to indicate relationsip among entities intended primarily for te

database design process%

Basic Symbo&s

ntity

elationsip

(ata 3tem

Stands for is aT

Primary ey

lass - s!b - class


3SA


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De'ree

#e n!mber of entities tat participate in a relationsip%

Most Ty,ica& De'rees #or Re&ations/i,

1. 3nary Re&ations/i, - relationsip between instances of te

entity class%

4%

. Binary Re&ations/i, - relationsip between instances of

two entity classes%

4%

=. Ternary Re&ations/i, - relationsip among instances of tree

entity classes%

4%


)P6@Y

PS@D

PAD# /36(

1S#@) @(

P@(1# VD(@


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SEAT7OR2:

&%' Ui+e two e4amples !sing 1nary, Binary and #ernary elationsips

43I9 =

8orma&i-in' a Database

8orma&i-ation

- is a process of red!cing red!ndancies of data in a database%

- is a tecni"!e tat is !sed wen designing and redesigning a database%

- is a process or set of g!idelines !sed to optimally design a database to red!ce red!ndant data%

T/e Ra% Database

A database tat is not normalied may incl!de data tat is contained in one or more different

tables for no apparent reason% #is co!ld be bad for sec!rity reasons, dis$ space !sage, speed of

"!eries, efficiency of database !pdates, and, maybe most importantly, data integrity% A database

before normaliation is one tat as not been bro$en down logically into smaller, more

manageable tables%

@)PADY;(A#ABAS

mp;id c!st;id

6ast;name c!st;name

?irst;name c!st;address

)iddle;name c!st;city

Address c!st;state

ity c!st;ip

State c!st;pone

Iip c!st;fa4

Pone ord;n!m

Pager "ty


.A/@1S


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Position ord;date

(ate;ire prod;id

Lo'ica& Database Desi'n

Any database so!ld be designed wit te end !ser in mind% 6ogical database design, also

referred to as te logical model, is te process of arranging data into logical, organied gro!ps of

ob>ects tat can easily be maintained% #e logical design of a database so!ld red!ce data

repetition or go so far as to completely eliminate it% After all, wy store te same data twiceQ

Daming con+entions !sed in a database so!ld also be standard and logical%

7/at are t/e End 3serFs 8eedsG

#e needs of te end !ser so!ld be one of te top considerations wen designing a database%

emember tat te end !ser is te person wo !ltimately !ses te database% #ere so!ld be ease

of !se tro!g te !serZs front-end tool a client program tat allows a !ser access to a database',

b!t tis, along wit optimal performance, cannot be acie+ed if te !serZs needs are not ta$en into

consideration%

Some !ser-related design considerations incl!de te following:

.at data so!ld be stored in te databaseQ

/ow will te !ser access te databaseQ

.at pri+ileges does te !ser re"!ireQ

/ow so!ld te data be gro!ped in te databaseQ

.at data is te most commonly accessedQ

/ow is all data related in te databaseQ

.at meas!res so!ld be ta$en to ens!re acc!rate dataQ



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Data redundancy

(ata so!ld not be red!ndant, wic means tat te d!plication of data so!ld be $ept to a

minim!m for se+eral reasons% ?or e4ample, it is !nnecessary to store an employeeZs ome

address in more tan one table% .it d!plicate data, !nnecessary space is !sed% onf!sion is

always a treat wen, for instance, an address for an employee in one table does not matc te

address of te same employee in anoter table%

.ic table is correctQ (o yo! a+e doc!mentation to +erify te employeeZs c!rrent addressQ As

if data management were not diffic!lt eno!g, red!ndancy of data co!ld pro+e to be a disaster%

T/e 8orma& orms

Dormal form is a way of meas!ring te le+els or dept, to wic a database as been

normalied% A databaseZs le+el of normaliation is determined by te normal form%

#e following are te tree most common normal forms in te normaliation process :

#e first normal form

#e second normal form

#e tird normal form

@f te tree normal forms, eac s!bse"!ent normal form depends on normaliation steps

ta$en in te pre+io!s normal form% ?or e4ample, to normalie a database !sing te

second normal form, te database m!st first be in te first normal form%

T/e irst 8orma& orm

#e ob>ecti+e of te first normal form is to di+ide te base data into logical !nits called

tables% .en eac table as been designed, a primary $ey is assigned to most or all

tables%

@)PADY ; (A#ABAS

)P6@Y ; #B6 1S#@) ; #B6emp;id emp;id c!st;id c!st;id

last;name last;name c!st;name c!st;name

first;name first;name c!st;address c!st;address

middle;name middle;name c!st;city c!st;city

address address c!st;state c!st;state



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city city c!st;ip c!st;ip

state state c!st;pone c!st;pone

ip ip c!st;fa4 c!st;fa4

pone pone ord;n!m ord;n!m

pager pager "ty "typosition position ord;date ord;date

position;desc postion;desc

date;ire date;ire prod;id

pay;rate pay;rate prod;desc P@(1#S;#B6

bon!s bon!s cost prod;id

date;last;raise date;last;raise prod;desc

cost

Yo! can see tat to acie+e te first normal form, data ad to be bro$en into logical

!nits of related information, eac a+ing a primary $ey and ens!ring tat tere are no

repeated gro!ps in any of te tables% 3nstead of te large table, tere are now smaller,

more manageable tables: )P6@Y;#B6, 1S#@);#B6 and P@(1#S;#B6%

#e primary $eys are normally te first col!mns listed in a table, in tis case: )P;3(

and P@(;3(%

T/e Second 8orma& orm

#e ob>ecti+e of te second normal form is to ta$e data tat is only partly dependent on

te primary $ey and enter tat data into anoter table%

)P6@Y;#B6 )P6@Y;#B6emp;id emp;id

last;name last;name

first;name first;name

middle;name middle;nameaddress address

city city

state state )P6@Y;PAY;#B6

ip ip emp;id

pone pone position

pager pager position;desc

position

position;desc date;ire

date;ire pay;rate

pay;rate bon!s

bon!s date;last;raise

date;last;raise



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1S#@);#B6

1S#@);#B6 c!st;idc!st;id c!st;name

c!st;name c!st;address

c!st;address c!st;city

c!st;city c!st;state

c!st;state c!st;ip

c!st;ip c!st;pone

c!st;pone c!st;fa4

c!st;fa4

@(S;#B6

ord;n!m

prod;id ord;n!m

"ty prod;idord;date "ty ord;date

?3S# D@)A6 ?@) S@D( D@)A6 ?@)

According to te fig!re, te second normal form is deri+ed from te first normal form

by f!rter brea$ing two tables down into more specific !nits%

)P6@Y;#B6 split into two tables called )P6@Y-#B6 and

)P6@Y;PAY;#B6% Personal employee information is dependent on te primary $ey

)P;3( ', so tat te information remained in te )P6@Y;#B6 )P;3(,

6AS#;DA), ?3S#;DA), )3((6;DA), A((SS, 3#Y, S#A#, I3P,

P/@D and PAU% @n te oter and, te information tat is only partly dependent

on te )P;3( eac indi+id!al employee ' is !sed to pop!late )P6@Y;PAY;#B6

)P;3(, P@S3#3@D, P@S3#3@D;(S, (A#;/3, PAY;A# and

(A#;6AS#;A3S '% Dotice tat bot tables contain te col!mn )P;3(% #is is te

primary $ey of eac table and is !sed to matc corresponding data between te two

tables%

1S#@);#B6 split into two tables called 1S#@);#B6 and @(S;#B6%

.at too$ place is similar to wat occ!rred in te )P6@Y;#B6% ol!mns tat

were partly dependent on te primary $ey were directed to anoter table% #e order

information for a c!stomer is dependent on eac 1S#;3(, b!t does not directly depend

on te general c!stomer information in te original table%



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T/e T/ird 8orma& orm

#e tird normal formZs ob>ecti+e is to remo+e data in a table tat is not dependent on

te primary $ey%

Anoter table was created to display te !se of te tird normal form%

)P6@Y;PAY;#B6 is split into two tables, one table containing te act!al employee

pay information and te oter containing te position descriptions, wic really do not

need to reside in )P6@Y-PAY;#B6% #e P@S3#3@D;(S col!mn is totally

independent of te primary $ey, )P;3(%

)P6@Y;PAY;#B6

emp;id

position

position;desc

date;ire

pay;rate

bon!s

date;last;raise

)P6@Y;PAY;#B6

emp;id P@S3#3@DS;#B6

position position

date;ire position-desc

pay;rate

bon!s

date;last;raise

Bene#its o# 8orma&i-ation

Dormaliation pro+ides n!mero!s benefits to a database% Some of te ma>or benefits

incl!de te following :

- Ureater o+erall database organiation

- ed!ction of red!ndant data

- (ata consistency witin te database design



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- A m!c more fle4ible database design

- A better andle on database sec!rity

%

Dra%bac0s o# 8orma&i-ation

Alto!g most s!ccessf!l databases are normalied to some degree, tere is one

s!bstantial drawbac$ of a normalied database: red!ced database performance% #e

acceptance of red!ced performance re"!ires te $nowledge tat wen a "!ery or

transaction re"!est is sent to te database, tere are factors in+ol+ed, s!c as P1 !sage,

memory !sage and inp!to!tp!t 3@'% #o ma$e a long story sort, a normalied database

re"!ires m!c more P1, memory and 3@ to process transactions and database "!eries

tan does a de-normalied database% A normalied database m!st locate te re"!ested

tables and ten >oin te data from te tables to eiter get te re"!ested information or to

process te desired data% A more in-dept disc!ssion concerning database performance

occ!rs in /o!r &8, )anaging (atabase 1sers%

43I9 ?

MIDTERM E;AMI8ATIO8

I8ALS PERIOD



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Lecture no. 1: TRA8SA)TIO8 MA8A


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(atabase and System atalog

i'ure 1

T/e DBMS Transaction Subsystem

1. )oncurrency )ontro&

)oncurrency )ontro& * te processof managing sim!ltaneo!s operations on tedatabase wito!t a+ing tem interfere wit one anoter%

Ma5or ob5ecti"e in de"e&o,in' a database

3s to enable many !sers to access sared data conc!rrentlyT

T/ree e+am,&es o# ,otentia& ,rob&ems caused by concurrency:

&%' T/e Lost 3,date Prob&em an apparently s!ccessf!lly completed !pdate

operations by one !ser can be o+erridden by anoter !ser%

2%' T/e 3ncommitted De,endency Prob&em occ!rs wen one transaction is

allowed to see te intermediate res!lts of anoter transaction before it ascommitted%

*%' T/e Inconsistent Ana&ysis Prob&em occ!rs wen a transaction !pdates some of

tem !sing te e4ec!tion of te first%

1.= Database Reco"ery

Database Reco"ery te process of restoring te database to a correct state in te e+entof a fail!re%

our di##erent ty,es o# media %it/ an increasin' de'ree #or re&iabi&ity:

&%' Main Memory is +olatile storage tat !s!ally does not s!r+i+e system crases%

2%' Ma'netic Dis0s pro+ide online non-+olatile storage% ompared wit main

memory, dis$s are more reliable and m!c ceaper, b!t slower by tree to fo!r

order of magnit!de%


Access )anager

Systems )anager

?ile )anager


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*%' Ma'netic Ta,e is an offline non-+olatile storage medi!m, wic is far morereliable tan dis$ and fairly ine4pensi+e, b!t slower, pro+iding only se"!ential

access%

5%' O,tica& Dis0s is more reliable tan tape, generally ceaper, faster, pro+idingrandom access%

Additiona& acts:

- Main memoryis also calledPrimary Storage%- Dis0s and ta,eare $nown as Secondary Storage%

- Stab&e stora'erepresents information tat as been replicated in se+eral

non-+olatile storage media !s!ally dis$' wit independent fail!re modes%

Amon' t/e causes o# #ai&ure are:

&%' System cras/es d!e to ardware or software errors, res!lting in loss of main

memory%

2%' Media #ai&ures s!c as ead crases or !nreadable media, res!lting in te lossof parts of secondary storage%

*%' A,,&ication so#t%are errors s!c as logical errors in te program tat isaccessing te database, wic ca!se one or more transaction to fail%

5%' 8atura& ,/ysica& disasters s!c as fire, floods, eart"!a$es, or power fail!res%

%' Sabota'e or can be called as intentional corr!ption or destr!ction of data,

ardware or software facilities%

T%o Princi,a& E##ects t/at %e need to consider:

&%' #e loss of main memory, incl!ding te database b!ffers%

2%' #e loss of te dis$ copy of te database%

A DBMS s/ou&d ,ro"ide t/e #o&&o%in' #aci&ities to assist %it/ reco"ery:

A bac$!p mecanism, wic ma$es periodic bac$!p copies of te database%

6ogging facilities, wic $eep trac$ of te c!rrent state of transactions anddatabase canges%

A cec$point facility, wic enables !pdates to te database tat are in progress

to be made permanent%



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A reco+ery manager, wic allows te system to restore te database to a

consistent state following a fail!re%

Lo' i&e

#o $eep trac$ of database transactions, te (B)S maintains a special file called a log

or >o!rnal' tat contains information abo!t all !pdates to te database%

T/e &o' may contain t/e #o&&o%in' data:

&%' Transaction Records, containing:

#ransaction identifier%

#ype of log record%

3dentifier of data item affected by te database action%

.! )/ec0,oint records

)/ec0,oint * te point of syncroniation between te database and tetransaction log file% All b!ffers are force-written to secondary storage%

)/ec0,oint are sc/edu&ed at ,redetermined inter"a&s and in"o&"e t/e #o&&o%in'

o,erations:

.riting all log records in main memory to secondary storage%

.riting te modified bloc$s in te database b!ffers to secondary storage%

.riting a cec$point record to te log file% #is record contains te identifiers ofall transactions tat are acti+e at te time of te cec$point%

Reco"ery Tec/niHues

&%' Reco"ery tec/niHues usin' de#erred u,date

.en a transaction starts, write a transaction startrecord to te log%

.en any write operation is performed, write a log record containing all te data

specified pre+io!sly e4cl!ding te before-image of te !pdate'% (o not act!allywrite te !pdate to te database b!ffers or te database itself%



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.en a transaction is abo!t to commit, write a transaction commit log record,

write all te log records for te transaction to dis$ and ten commit tetransaction% 1se te log records to perform te act!al !pdates to te database%

3f a transaction aborts, ignore te log records for te transaction and do notperform te writes%

Any transaction wit transaction startand transaction commitlog records so!ld

be redone%

?or any transactions wit transaction startand transaction abortlog records, we

do noting, since no act!al writing was done to te database, so tese transactions

do not a+e to be !ndone%

2%' Reco"ery tec/niHues usin' immediate u,date

.en a transaction starts, write a transaction startrecord to te log%

.en a write operation is performed, write a record containing te necessary

data to te log file%

@nce te log record is written, write te !pdate to te database b!ffers%

#e !pdates to te database itself are written wen te b!ffers are ne4t fl!sed

to secondary storage%

.en a transaction commits, write a transaction committo te log%

Lecture no. : IMPRO>I8< 43ERY PERORMA8)E

.1 (as/ i&es

(as/ #unction * calc!lates te address of te page in wic te record is to be stored

based on one or more of te fields in te record%

(as/ #ie&d is also called as base field%

(as/ 0ey if te field is also a $ey field of te file%

)o&&ision wen te same address is generated for two or more records%



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T/ere are se"era& tec/niHues t/at can be used to mana'e co&&isions:

&%' @pen addressing

2%' 1ncained o+erflow*%' ained o+erflow

5%' )!ltiple asing

. Inde+es

Inde+es * a data str!ct!re tat allows te (B)S to locate partic!lar records in a file

more "!ic$ly, and tereby speed response to !ser "!eries%

Data #i&e te file containing te logical records%

Inde+ #i&e te file containing te inde4 records%

Primary inde+ if te data file is se"!entially ordered, and te inde4ing

field is a $ey field of te file, it is g!aranteed to a+e a !ni"!e +al!e in

eac record%

)&usterin' inde+ if te inde4ing is not a $ey field of te file, so tat

tere can be more tan one record corresponding to a +al!e of te

inde4ing field%

Secondary inde+ an inde4 tat is defined on a non-ordering field of te

data file%

Inde+ed seHuentia& #i&e a sorted data file wit a primary inde4%

An 3nde4ed se"!ential file is a more +ersatile str!ct!re, wic normally as:

A primary storage area%

A separate inde4 or inde4es%

An o+erflow area%

SEAT7OR2:

&%' (efine #ransaction

2%' Ui+e oter (atabase reco+ery tecni"!es

43I9 @

Lecture no. =: DATA 7ARE(O3SI8ect-oriented, integrated, time-+ariant, and non-+olatile



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collection of data in s!pport of managementZs decision-ma$ing process%

Bene#its o# Data 7are/ousin'

Potential ig ret!rns on in+estment ompetiti+e ad+antage

3ncreased prod!cti+ity of corporate decision-ma$ers

Prob&ems o# Data 7are/ousin'

1nderestimation of reso!rces for data loading

/idden problems wit so!rce systems

e"!ired data not capt!red

3ncreased end-!ser demands

(ata omogeniation /ig demand for reso!rces

(ata ownersip

/ig maintenance

6ong d!ration pro>ects

omple4ity of integration

T/e Ma5or com,onents o# a Data 7are/ouse

1. O,erationa& Data

T/e source o# data #or t/e data %are/ouse is su,,&ied #rom:

)ainframe operational eld in first generation ierarcical and networ$

databases%

(epartmental data eld in propriety file systems s!c as VSA), )S, and

relational (B)S s!c as 3nformi4, @racle%

Pri+ate data eld on wor$stations and pri+ate ser+ers%

4ternal systems s!c as te 3nternet, commercially a+ailable databases, or

databases associated wit an organiationZs s!pplier or c!stomers%

2% Load Mana'er also called tefront-endcomponent' performs all te

operations associated wit te e4traction and loading of data into te wareo!se%

*% 7are/ouse Mana'er performs all te operations associated wit te

management of te data in te wareo!se%

5% 4uery Mana'er - also called te back-endcomponent' performs all te

operations associated wit te management wit te management of !ser "!eries%

% End$user access too&s is to pro+ide information to b!siness !sers for strategicdecision ma$ing%

)an be cate'ori-ed into #i"e main 'rou,s:



36/37



eporting and "!ery tools%

Application de+elopment tools%

4ec!ti+e information system 3S' tools%

@nline analytical processing @6AP' tools%

(ata mining tools%

*%2 On&ine Ana&ytica& Processin' OLAP! te dynamic syntesis, analysis, andconsolidation of large +ol!mes of m!lti-dimensional data%

Ru&es #or OLAP Systems

)!lti-dimensional concept!al +iew

#ransparency

Accessibility

onsistent reporting performance lient-ser+er arcitect!re

Ueneric dimensionality

(ynamic sparse matri4 andling

)!lti-!ser s!pport

1nrestricted cross-dimensional operations

3nt!iti+e data manip!lation

?le4ible reporting

1nlimited dimensions and aggregations

)ate'ories o# OLAP Too&s

1. Mu&ti$dimensiona& OPLAP MOLAP or MD-OPLAP! !se specialieddata str!ct!res and )!lti-dimensional (atabase )anagement

)((B)Ss' to organie, na+igate, and analye data%

. Re&ationa& OPLAP ROLAP! is te fastest-growing style of @6AP

tecnology% @6AP s!pports (B)S prod!cts tro!g te !se of a

meta-data layer, t!s a+oiding te re"!irement to create a static m!lti-

dimensional data str!ct!re%

=. Mana'ed 4uery En"ironment (MQE

) tey pro+ide limited analysis

capability, eiter directly against (B)S prod!cts, or by !sing anintermediate )@6AP ser+er%

=.= Data Minin'

Data Minin' te process of e4tracting +alid, pre+io!sly !n$nown, compreensible, and

actionable information from large databases !sing it to ma$e cr!cial b!siness decisions%

our Main O,erations Associated %it/ Data Minin' Tec/niHues:

&% Predicti+e modeling *% 6in$ analysis

2% (atabase segmentation 5% (e+iation detection



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43I9

I8AL E;AMI8ATIO8

Documents

MELJUN CORTES MANUAL DataBase System CSCI12