dbms-handbook.doc

8/10/2019 dbms-handbook.doc

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Dept. of Computer Science Engineering, School of Engineering,Anurag Group of Institutions

%nderstandin! data, information, database and D&MS' Development and need of D&MS %nderstandin! architect"re of D&MS, $eople associated with the Database (ecessity and benefits of E)R dia!ram

Plan of "ecture Delivery:#o$ic %o of &ours Date 'emar( Information, Data,Database, D&MS, FileSystem

*+

Views, Instances,Abstraction and Schema *+Data Models, ER dia!rams,ER Model *+Relational Model, therModels, Database

an!"a!es DD , DM *+

-"torial *+$eople associated with theDatabase "sers,administrators anddevelopers

*+

Database, D&MS,Application pro!rams,-ransaction Mana!ement *+D&MS str"ct"re, Stora!e

Mana!er

*+

#"ery $rocessor, Revisionof -opics

*+

#otal )*

+m$ortant ,uestionsne mar. /"estions and answers0)

+' what are the main f"nctions of D&A a"thori1in! "sers to access the database coordinatin!2monitorin! its "se ac/"irin! hardware2software reso"rces for "p!rades

3' what is meant by data independence

Data inde$endence is the capacity to chan!e the schema at one level of the architect"rewitho"t havin! to chan!e the schema at the ne4t hi!her level' 5e distin!"ish betweenlogical and $hysical data independence accordin! to which two ad6acent levels areinvolved' -he former refers to the ability to chan!e the concept"al schema witho"t

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chan!in! the e4ternal schema' -he latter refers to the ability to chan!e the internalschema witho"t havin! to chan!e the concept"al'

"ogical Data +nde$endence:

-he capacity to chan!e the concept"al schema witho"t havin! to chan!e the e4ternalschemas and their associated application pro!rams'

Physical Data +nde$endence:

-he capacity to chan!e the internal schema witho"t havin! to chan!e the concept"alschema'

7' what are advanta!es of views0 Views are virt"al 8not real b"t in effect9 tables or relations which are based on "ser:sview of partic"lar data base'

;' what is relational schema Representation of relational database


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H' what is data model

A data model )))a collection of concepts that can be "sed to describe theconcept"al2lo!ical str"ct"re of a database))) provides the necessary means to achieve thisabstraction'

&y structure is meant the data types, relationships, and constraints that sho"ld hold for the data' Most data models also incl"de a set of basic o$erations for specifyin!retrievals2"pdates'' what is data red"ndancy

Repeatin! the same data a!ain and a!ain is nothin! b"t red"ndancy'Data red"ndancy8s"ch as tends to occ"r in the Jfile processin!J approach9 leads to /asted storage s$ace ,du$lication of effort 8when m"ltiple copies of a dat"m need to be "pdated9, and a hi!her li.elihood of the introd"ction of inconsistency 'K' write abo"t (aLve "sers

%aive0Parametric end users 0 -ypically the bi!!est !ro"p of "sers fre/"ently/"ery2"pdate the database "sin! standard canned transactions that have beencaref"lly pro!rammed and tested in advance' E4amples0

ii' ban. tellers chec. acco"nt balances, post withdrawals2deposits

iii' reservation cler.s for airlines, hotels, etc', chec. availability of seats2rooms and ma.ereservations'

iv' shippin! cler.s 8e'!', at %$S9 who "se b"ttons, bar code scanners, etc', to "pdate stat"sof in)transit pac.a!es'

+*' what is D&MSDatabase mana!ement system is software of collection of small pro!rams to performcertain operation on data and mana!e the data'

-wo basic operations performed by the D&MS are0 NMana!ement of Data in the Database NMana!ement of %sers associated with the database'

++' what is Relational al!ebra

Relational al!ebra and relational calc"l"s are formal lan!"a!es associatedwith the relational model'

Informally, relational al!ebra is a 8hi!h)level9 proced"ral lan!"a!e andrelational calc"l"s a non)proced"ral lan!"a!e'

Relational al!ebra operations wor. on one or more relations to define another relation witho"t chan!in! the ori!inal relations'

+3' define catalo!



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Syllabus:

Bistory of Database Systems, Database Desi!n and ER dia!rams, &eyond ER desi!n entities,Attrib"tes and Entity Sets, Relationships and Relationship Sets, Additional feat"res of ER model,?oncept Desi!n with ER Model, ?oncept"al Desi!n for ar!e Enterprises .

Ob ectives:

+9 -o learn abo"t the ER dia!rams39 ?oncepts of Attrib"tes and Entity sets79 Relationship and Relationship sets;9 earn abo"t the Desi!n iss"es of a database

#ime #able:

#o$ic %o of &ours DateBistory of D&MS,Database desi!n, ER desi!n,

)3

&eyond ER desi!n,Entities, Attrib"tes

)3

Entities, Relationshipand Relationship sets

)3

Additional Feat"res of ER model

)3

-"torial )3?oncept desi!n withER model

)3

?oncept"al desi!n for ar!e DatabaseSystems

)3

#otal )4

+m$ortant ,uestions:$revio"s one mar. /"estions "p to first two "nits0)

+;' what are the main f"nctions of D&A

+=' what is meant by data independence

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+>' what are advanta!es of views

+H' what is relational model

+ ' what is referential inte!rity

+K' what is meant by m"ltival"ed attrib"te3*' what is relational schema

3+' what is DD

33' what is ?artesian prod"ct

37' what is inte!rity constraint

3;' what is meta data

3=' note on "pdate command

3>' what is data model

3H' list all types of S#

3 ' what is data red"ndancy

3K' write abo"t (aLve "sers

7*' what is an wea. entity set

7+' write abo"t composite attrib"te

73' define candidate .ey

77' what is D&MS

7;' what is RD&MS7=' what is Relational al!ebra

7>' write the "se of m"ltival"ed attrib"te

7H' what are s/l lan!"a!es

7 ' define catalo!

7K' define Data Dictionary

;*' define concept"al schema

;+' what is relation ship instance

;3' what is .ey constraint

;7' what is forei!n .ey constraint

;;' how to represent m"ltival"ed attrib"te in E'R model

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$revious $a$er long ans/er 5uestions

3. Describe the three schema architect"re' 5hy do we need mappin! b2w schema levels6. list the cases in which n"ll val"es are appropriate with e4amples

7. differentiate b2w F$S and D&MS

8. desi!n a concept"al data base desi!n for health ins"rance system

9. compare and contrast Relational model and Bierarchical model

. e4plain the basic operations of Relational Al!ebra with e4amples

4. Draw and e4plain the D&MS component mod"les

;. what are advanta!es of D&MS

*. e4plain the difference b2w amon! entity, entity type and relation ship set

3). what is inte!rity constraint e4plain deferent constraints in D&MS

33. what are the f"nctions of D&A

36. write abo"t architect"re of D&MS

37. e4plain abo"t vario"s database "sers

38. what are vario"s capabilities of D&MS

39. what is the difference b2w lo!ical data independence and physical data independence

3 . disc"ss the the main types of constraints on speciali1ation and !enerali1ation34. what is e)r model 'e4plain the components E)R model

3;. what is s/l and vario"s types of commands

3*. e4plain abo"t relation model and advanta!es of rm'

APP"+-A#+O%S:

+9 5ritin! ER Model39 Desi!n iss"es of Database

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Syllabus:

Introd"ction to Relational Model Inte!rity constraint over relations, enforcin! inte!rity

constraints, /"eryin! relational data, lo!ical database desi!n, introd"ction to views,destroyin!2alterin! tables and views'

Relational Al!ebra Selection and $ro6ection set operations, renamin!, 6oins, divisions, E4ampleof Al!ebra overviews, relational calc"l"s, t"ple relational calc"l"s, domain relational calc"l"s,e4pressive power of al!ebra and calc"l"s'

Ob ectives of !nit:

+9 Introd"ction to Relational Model, Inte!rity constraints over relations39 #"eryin! relational data, lo!ical database desi!n, introd"ction to views and tables

79 Relational al!ebra pro6ection and selection, relational calc"l"s;9 Domain relational calc"l"s, e4pressive power of al!ebra and calc"l"s

#eaching Plan:

#o$ic %o of &ours Date 'emar( Relational Model,Inte!rity ?onstraints,#"eryin! relationalmodel

*+

o!ical Database

desi!n, introd"ction toviews

*+

Destroyin!2alterin!tables

*+

Relational Al!ebra *+-"torial *+Selection and$ro6ection

*+

Ooins, renamin! *3-"ple relational?alc"l"s

*+

Domain relationalcalc"l"s

*+

-"torial *+E4pressive power ofal!ebra and calc"l"s

*+

#otal 36

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+m$ortant ,uestions:

Re/"irements Analysis

"ser needs what m"st database doP

?oncept"al Desi!n hi!h level description 8often done with ER model9

o!ical Desi!n translate ER into D&MS data model8Relational model9

8( 59Schema Refinement consistency,normali1ation

$hysical Desi!n) inde4es, dis. layo"t

Sec"rity Desi!n) who accesses what

Qood Database Desi!n

no red"ndancy of FACT (!)no inconsistency

no insertion, deletion or "pdate anomaliesno information lossno dependency loss

Informal Desi!n Q"idelines for Relational Databases+' Semantics of the Relation Attrib"tes3' Red"ndant Information in -"ples and %pdate Anomalies7' ("ll Val"es in -"ples;' Sp"rio"s -"ples

3. Semantics of the 'elation Attributes

Q%IDE I(E +0 Informally, each t"ple in a relation sho"ld represent one entity or relationship instance' 8Applies to individ"al relations and their attrib"tes9'

o Attrib"tes of different entities 8EM$ EEs, DE$AR-ME(-s, $R OE?-s9sho"ld not be mi4ed in the same relation

o nly forei!n .eys sho"ld be "sed to refer to other entities



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o Entity and relationship attrib"tes sho"ld be .ept apart as m"ch as possible' Design a schema that can be explained easily relation by relation. The semantics of attributes should be easy to interpret.

6. 'edundant +nformation in #u$les and !$date Anomalies

Information is stored red"ndantlyo 5astes stora!eo ?a"ses problems with "pdate anomalies

Insertion anomaliesDeletion anomaliesModification anomalies

?onsider the relation0EM$T$R O8EmpU, $ro6U, Ename, $name, (oTho"rs9

+nsertion anomalies

?annot insert a pro6ect "nless an employee is assi!ned to it'

Deletion anomaliesa' 5hen a pro6ect is deleted, it will res"lt in deletin! all the employees who wor. on

that pro6ect' b' Alternately, if an employee is the sole employee on a pro6ect, deletin! that

employee wo"ld res"lt in deletin! the correspondin! pro6ect'

Modification anomalies?han!in! the name of pro6ect n"mber $+ from &illin!G to ?"stomer)Acco"ntin!G mayca"se this "pdate to be made for all +** employees wor.in! on pro6ect $+'

Q%IDE I(E 30Desi!n a schema that does not s"ffer from the insertion, deletion and "pdateanomalies'If there are any anomalies present, then note them so that applications can bemade to ta.e them into acco"nt'

7. %ull


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Reasons for n"lls0Attrib"te not applicable or invalidAttrib"te val"e "n.nown 8may e4ist9Val"e .nown to e4ist, b"t "navailable

A$$lications:+9 %nderstandin! the nat"re of D&MS39 Relational Al!ebra and calc"l"s

Students e1$ected to learn:Relational Al!ebra, relational calc"l"s



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!nit2+%on2additive? Join Pro$erty of a Decom$osition:Definition0 ossless 6oin property0 a decomposition D R+, R3, ''', RmW of R has the lossless >nonadditive? oin $ro$erty with respect to the set of



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dependencies F on R if, for e#ery relation state r of R that satisfies F, thefollowin! holds, where is the nat"ral 6oin of all the relations in D0

8 R+8r9, ''', Rm8r99 r

Multi2valued de$endency >Mfor e1am$le A@ and -? in a relation such that for each value of A there is aset of values for @ and a set of value for -. &o/ever the set ofvalues for @ and - are inde$endent of each other.

A multi2valued de$endency can be further defined as beingtrivial or nontrivial. A MVD A ^ & in relation R is definedas bein! trivial if

& is a s"bset of Aor

A % & RA MVD is defined as bein! nontrivial if neither of the above twoconditions is satisfied'

Fourth normal form >8%F?A relation that is in @oyce2-odd normal form and containsno nontrivial multi2valued de$endencies.

A relation schema $ is in 8%F with respect to a set of dependencies F 8that incl"desf"nctional dependencies and m"ltival"ed dependencies9 if, for every nontri#ial m"ltival"ed dependency % ^^ & in F @, % is a s"per.ey for R'

Definition:A oin de$endency 8JD 9, denoted by OD8 $ +, $ 3, ''', $ n9, specified on relation schema $ ,specifies a constraint on the states r of $ '

-he constraint states that every le!al state r of $ sho"ld have a non)additive 6oindecomposition into $ +, $ 3, ''', $ n that is, for every s"ch r we have

8 $' 8r 9, $ 8r 9, ''', $n 8r 99 r Note an *+D is a special case of a ,D -here n .A 6oin dependency OD8 $ +, $ 3, ''', $ n9, specified on relation schema $ , is a trivial JD if

one of the relation schemas $ i in OD8 $ +, $ 3, ''', $ n9 is e/"al to $ '

Fifth normal form >9%F?Definition:

A relation schema $ is in fifth normal form 89%F 9 8or Pro ect2Join %ormal Form8PJ%F 99 with respect to a set F of f"nctional, m"ltival"ed, and 6oin dependencies if,



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for every nontrivial 6oin dependency OD8 $ +, $ 3, ''', $ n9 in F @ 8that is, implied by F 9,

every $ i is a s"per.ey of $ '

Each normal form is strictly stron!er than the previo"s oneEvery 3(F relation is in +(FEvery 7(F relation is in 3(FEvery &?(F relation is in 7(F

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Every ;(F relation is in &?(FEvery =(F relation is in ;(F

Dia!rammatic notation of normal forms0)

(ormali1ation_NA techni/"e for prod"cin! a set of relations with desirable

properties, !iven the data re/"irements of an enterprise_N%(F is a table that contains one or more repeatin! !ro"ps_N+(F is a relation in which the intersection of each row and col"mn contains one

and only one val"e_N3(F is a relation that is in +(F and every non)primary).ey attrib"te is f"llyf"nctionally dependent on the primary .ey'_N7(F is a relation that is in +(F, 3(F in which no non)primary).ey attrib"te istransitively dependent on the primary .ey_N&?(F is a relation in which every determinant is a candidate .ey_N;(F is a relation that is in &?(F and contains no trivial m"lti)val"eddependency

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res"lts of a transaction and therefore either all actions of a transaction are completed or the transaction has no effect on the database' -herefore a transaction is either completeds"ccessf"lly or rolled bac.' -his is sometime called all2or2nothing '

6. Define seriali=ability of transactionsSeriali1ability is a !iven set of interleaved transactions is said to be seriali1able if andonly if it prod"ces the same res"lts as the serial e4ec"tion of the same transactions'

7. Bhat is functional de$endencyA f"nctional dependency is a property of the semantics of the attrib"tes in a relation' -hesemantics indicate how attrib"tes relate to one another, and specify the f"nctionaldependencies between attrib"tes' 5hen a f"nctional dependency is present, thedependency is specified as a constraint between the attrib"tes'?onsider a relation with attrib"tes A and &, where attrib"te & is f"nctionally dependenton attrib"te A' If we .now the val"e of A and we e4amine the relation that holds thisdependency, we will find only one val"e of & in all of the t"ples that have a !iven val"eof A, at any moment in time' (ote however, that for a !iven val"e of & there may beseveral different val"es of A'

In the fi!"re above, A is the determinant of & and & is the conse/"ent of A'-he determinant of a f"nctional dependency is the attrib"te or !ro"p of attrib"tes on theleft)hand side of the arrow in the f"nctional dependency' -he conse/"ent of a fd is theattrib"te or !ro"p of attrib"tes on the ri!ht)hand side of the arrow'

8. Bhat is %ormali=ation-he process of decomposin! "nsatisfactory JbadJ relations by brea.in! "p their attrib"tes into smaller relations'

(ormali1ation is a process of analy1in! relation schemas so that the followin!can be achieved

+' Minimi1in! red"ndancy3' Minimi1in! insertion, "pdatin!, deletion anomalies

9. Bhat is revo(e commandRevo.e is a DD command which is "sed to disallow the privile!es that are !ranted byD&A "sin! Qrant command'

. Bhat is #ransactionDef 3 0 o!ical "nit of database processin! that incl"des one or more access operations8read )retrieval, write ) insert or "pdate, delete9'

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Def 6 0 -ransaction is an e4ec"tin! pro!ram formin! a lo!ical "nit of database accessoperations that involves one or more database operations 8read )retrieval, write ) insert or "pdate, delete9'

-ransaction bo"ndaries0o &e!in and End transaction'

An application pro!ram may contain several transactions separated by the &e!in andEnd transaction bo"ndaries'

&asic operations are read and writeo readTitem8[90 Reads a database item named [ into a pro!ram variable' -o

simplify o"r notation, we ass"me that the pro!ram variable is also named ['o writeTitem8[90 5rites the val"e of pro!ram variable [ into the database item

named ['4. Bhat is #rigger

-ri!!ers are simply stored proced"res that are ran a"tomatically by the database

whenever some event happens';. Bhat is the use of seriali=ability Achievin! conc"rrency by e4ec"tin! no' of transactions at a time Fast response to the "ser with correct res"lt %tili1ation of reco"rses efficiently

*. Bhat are transaction $rimitives-ransaction bo"ndaries are nothin! b"t transaction primitives' -hey are@egin #ransaction and nd #ransaction.

3). Bhat is an AssertionAssertion is nothin! b"t a name !iven to a set of "ser defined constraints'

33. Bhat are uses of #ransaction It:s all abo"t fast /"ery response time and correctness D&MS is a m"lti)"ser systems

o Many different re/"estso Some a!ainst same data items

Fi!"re o"t how to interleave re/"ests to shorten response time while !"aranteein!correct res"lt

o Bow does D&MS .now which actions belon! to!etherP Sol"tion0 Qro"p database operations that m"st be performed to!ether into transactions

o Either e4ec"te all operations or none

36. Bhat are Anomalies Refers to a deviation from the common r"le8s9, type8s9, arran!ement8s9, or form8s9' -he !eneral anomalies are insertion, "pdation, and deletion anomalies'

37. Define vie/ seriali=abilityView e/"ivalence0 -wo sched"les are said to be view e/"ivalent if the followin! three conditions hold0



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+' -he same set of transactions participates in S and S:, and S and S: incl"de thesame operations of those transactions'

3' For any operation Ri8[9 of -i in S, if the val"e of [ read by the operation has been written by an operation 568[9 of -6 8or if it is the ori!inal val"e of [ before the sched"le started9, the same condition m"st hold for the val"e of [read by operation Ri8[9 of -i in S:'

7' If the operation 5.8 9 of -. is the last operation to write item in S, then5.8 9 of -. m"st also be the last operation to write item in S:'

View seriali1ability0 Definition of seriali1ability based on view e/"ivalence' A sched"le is #ie- seriali/able if it is #ie- e0ui#alent to a serial sched"le'

38. Bhat are transaction $ro$erties Atomicity 0 A transaction is an atomic "nit of processin! it is either performed in its

entirety or not performed at all' -onsistency $reservation 0 A correct e4ec"tion of the transaction m"st ta.e the

database from one consistent state to another' +solation 0 A transaction sho"ld not ma.e its "pdates visible to other transactions "ntil

it is committed this property, when enforced strictly, solves the temporary "pdate problem and ma.es cascadin! rollbac.s of transactions "nnecessary '

Durability or $ermanency 0 nce a transaction chan!es the database and the chan!esare committed, these chan!es m"st never be lost beca"se of s"bse/"ent fail"re'

39. Define "atchesoc.s held for a short d"ration are called atches' atches do not follow conc"rrency

methods rather than they "sed to !"arantee the physical inte!rity of a pa!e when that pa!e bein! written from the b"ffer to dis.'

3 . Define 1clusive loc( E4cl"sive loc. is a loc. which specifies that no other transaction can able to access thedata item, e4cept the c"rrent transaction which holds it' Qenerally write loc. is called asE4cl"sive loc.'

34. Define -ertify loc( ?ertify loc. is a loc. "sed in m"lti version conc"rrency techni/"e to certify that the newversion created d"rin! write operation is !oin! to be stored permanently in database'

3;. Define CranularityQran"larity means si1e of data item which may be one of the followin!

+' A database record3' A field val"e of a database record7' A dis. bloc. ;' A whole file=' -he whole database



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