Logical Rdm Standard

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Property and Casualty Insurance Working Group

Logical Relational Data ModelingStandardsVersion 1.0

June 16, 2008
http://www.omg.org/


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Table of ContentsIntroduction................................................................................................................ 3

Purpose................................................................................................................... 3

Document Maintenance..........................................................................................3

Scope...................................................................................................................... 3

Logical Relational Data Model Defnition....................................................................3

ER Diagramming Conventions.................................................................................... 4

Modeling Synta ......................................................................................................4

Diagramming Layout !uidelines............................................................................."

#ormal $orms..........................................................................................................%

&riting Defnitions o' Logical ()*ects.........................................................................%

Logical ()*ect Defnition !uidelines+....................................................................... %

Entity Defnition !uidelines+.................................................................................... %

,ttri)ute Defnition !uidelines+............................................................................... %

#aming Logical ()*ects.............................................................................................. -

Logical ()*ect #aming !uidelines...........................................................................-

Entity #aming !uidelines........................................................................................ -,ttri)ute #aming !uidelines...................................................................................

Relations/ip #aming !uidelines.............................................................................. 0

Relations/ip Standards............................................................................................... 0

Super1types and Su)1types.......................................................................................2

Entity eys................................................................................................................ 22

Dimensional Data Modeling...................................................................................... 25

,ppendi .................................................................................................................. 23

Class &ords........................................................................................................... 23

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Introduction

Purpose 6/is document provides standards and guidance 'or t/e naming and use o' o)*ectsin logical relational data models. Logical o)*ects are created and maintained tomeet )usiness re7uirements. ,ccurate naming clarifes t/e specifc nature o' eac/logical o)*ect. Consistency allo8s t/e logical names to /ave persistent value indi9erentiating data items. #ame 'ormation and t/e use o' logical modeling o)*ectsare independent o' any particular data modeling tool or relational data)asemanagement system :RD;MS< plat'orm. 6/ese logical relational data modelingguidelines are independent o' specifc C,SE tools.

6/e intention o' t/is standard is to esta)lis/ an agreed1upon )asis 'or developinglogical relational data models in order to promote greater 7uality and consistency

across data models and ena)le o)*ective model revie8s.Document Maintenance

6o suggest improvements= c/anges or additions to t/is standard= contact+

!ail ,ustin or >ars/ S/arma

gail.austin?gmail.com s/arma/8?ya/oo.com

Scope 6/ese standards apply to all logical relational data models t/at are developed )y(M! su)mission teams.

Logical Relational Data Model De nition 6/e relational model 'or data)ase management is a data)ase model )ased onpredicate logic and set t/eory. It 8as frst 'ormulated and proposed in 20%0 )yEdgar Codd 8it/ aims t/at included avoiding= 8it/out loss o' completeness= t/eneed to 8rite computer programs to e press data)ase 7ueries and en'orcedata)ase integrity constraints. @RelationA is a mat/ematical term 'or @ta)leA= andt/us @relationsA roug/ly means @)ased on ta)lesA. It does not re'er to t/e linBs or@BeysA )et8een ta)les= contrary to popular )elie'. 2

, logical relational data model defnes 8/at an organi ation Bno8s a)out t/ings o'interest to t/e )usiness and grap/ically s/o8s /o8 t/ey relate to eac/ ot/er in anentity relations/ip :ER< diagram. ,n entity relations/ip diagram is an a)stractconceptual representation o' structured data. It uses standard sym)ols to denotet/e t/ings o' interest to t/e )usiness :entities


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Data Model= in contrast to t/e more a)stract Conceptual Relational Data Model=contains detailed c/aracteristics o' t/e entities :attri)utes< and t/eir defnitions. Itgenerates t/e structure o' a p/ysical data model 8/ic/ in turn generates adata)ase 'ollo8ing Model Driven ,rc/itecture principles. It is a result o' detailedanalysis o' t/e )usiness re7uirements.

6/e 'ollo8ing illustration s/o8s /o8 t/e logical model fts into t/e overall datamodeling process+

ltimately= t/e logical relational data model /elps to solidi'y and validate )usinessre7uirements and delivers sta)le= Fe i)le data structures t/at are easily navigatedand can ans8er unanticipated 7uestions.

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ER Diagramming Conventions

Modeling Synta 6/e recommended notation 'or models is In'ormation Engineering :IE< @Cro8Gs$eetA 1 )ecause it is easier 'or users to interpret t/an t/e Integration Defnition 'orIn'ormation Modeling :IDE$2H< notation. 5

Diagramming Layout !uidelines(rient entities so t/at t/e @toesA o' a relations/ipGs cro8Gs 'oot al8ays point do8n.

6/is puts 'undamental entities in t/e top area o' t/e diagram= and positionsassociative and su)type entities in t/e lo8er area o' t/e diagram.

Recommended cro8Gs 'eet do8n convention ,void dead cro8s

CONTACT PROFILE

Person Identifier (FK)Contact Point Identifier (FK)

Home Contact Point Indicator Work Contact Point Indicator

CONTACT POINT

Contact Point Identifier

PERSON

Person Identifier (FK)

First N ameMiddle NameLast NameLegal NameNicknameName Suffix

irt! "ateirt! Place Name

#ender Code

CONTACT PROFILE

Person Identifier (FK)Contact Point Identifier ( FK)

Home Contact Point Indicator Work Contact Point Indicator

CONTACT POINT

Contact Point Identifier

PERSON

Person Identifier (FK)

First N ameMiddle NameLast NameLegal Name

NicknameName Suffix

irt! "ateirt! Place Name

#ender Code

eep t/e relations/ip lines as straig/t as possi)le. ,void unnecessary )ends. 6oomany sym)ols clutter t/e diagram and maBe it con'using to t/e vie8er.

,void crossing relations/ip lines. Crossed lines maBe it diJcult to understand 8/ic/entities are related.

Relations/ip names s/ould )e placed on t/e diagram so t/at t/e ver)s or ver)p/rases are read in a clocB8ise direction 'rom one entity to t/e related entity.

E ample+

5 6/e c/oice o' IE notation 8ill )e revisited 8/en t/e ;arBer notation )ecomes more 8idelyavaila)le in t/e modeling tools.

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Property and Casualty Insurance Working GroupPOLIC

Polic$ Identifier

E!POS"RE

Polic$ Identifier (FK)Insured %&'ect Identifier (FK)Co erage $*e Identifier (FK)

co ers

is co ered &$

"ormal #orms#ormal $orms provide a 8ay to structure data to eliminate undesira)leredundancies= inconsistencies and dependencies. #ormali ation is a 'ormali edtec/ni7ue 'or creating t/e most desira)le logical model 'or t/e given data and)usiness rules. Completed logical models s/ould )e in= at least= ;oyceKCodd #ormal$orm :;C#$< 3 . $or a model to )e in ;C#$= every entity in t/e model must )e in;C#$. 6/e normal 'orms are summari ed )elo8+

First Normal Form (1NF) identifes and eliminates repeating groups andesta)lis/es a primary Bey.

Second Normal Form (2NF) identifes and removes partial1Bey dependencies. 6/is applies only to ta)les 8it/ composite Beys.

Third Normal Form (3NF) identifes and eliminates non1Bey attri)utes t/at aredependent on ot/er non1Bey attri)utes.

o!ce"#odd Normal Form ( #NF) identifes and eliminates Bey attri)utes t/at aredependent upon ot/er Bey attri)utes in an entity 8it/ a composite Bey.

$riting De nitions of Logical %b&ects!ood Logical ()*ect names are important )ecause t/ey provide a persistent recordo' t/e uni7ue nature o' eac/ o)*ect. !ood names cannot )e developed unless t/eo)*ect frst /as a good )usiness defnition.

Logical %b&ect De nition !uidelines' se industry defnitions 8/ere possi)le and appropriate. Descri)e 8/at t/e entity or attri)ute is not 8/ere= 8/en or )y 8/om it is

used.

3 See &iBipedia Data)ase #ormali ation+/ttp+KKen.8iBipedia.orgK8iBiKData)ase normali ation

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;e clear and concise. &rite as i' t/e reader is un'amiliar 8it/ t/e )usiness area. se )usiness terms rat/er t/an tec/nical terms to e press t/e meaning and

importance to t/e )usiness. se mi ed case according to standard )usiness Englis/ conventions. Do not use *argon= a))reviations or acronyms. Do not include in'ormation t/at s/ould )e documented else8/ere= suc/ as

process descriptions.

Entity De nition !uidelines' Entity defnitions s/ould )e ro)ust and communicate t/e essential and uni7ue

)usiness nature o' t/e entity. Do not depend on or re'er to t/e defnition o' anot/er o)*ect in t/e model. E press one concept or idea eac/ entity s/ould /ave a uni7ue meaning.

(ttribute De nition !uidelines' ,ttri)ute defnitions s/ould communicate t/e essential )usiness nature and

purpose o' t/e attri)ute. Do not depend on or re'er to t/e defnition o' anot/er o)*ect in t/e model=

e cept 'or derived attri)utes. Include t/e domain o' allo8ed values and de'ault value 8/ere appropriate.

"aming Logical %b&ects

Logical %b&ect "aming !uidelines se one or more 8ords 8/ic/ are 'ormed using t/e 5% letters :,1


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series o' 8ords= as radar 'or ra dio d etecting a nd r anging. &/en an acronymis 8idely Bno8n it may )e an e ception to t/e no a))reviation rule. , list o'e ceptions s/ould )e maintained as an appendi to t/is standard andsu)*ect to an approval and a governance process.

,))reviations i' t/e o)*ect name is too long to ft in t/e space allotted )yt/e data modeling tool and all non1essential 8ords /ave )een eliminated'rom t/e name= a))reviate t/e class 8ord. I' t/e name is still too long= fndte t in t/e name t/at can 'orm acronyms. Starting 8it/ t/e rig/t1most te t=apply t/e acronym and repeat moving le't in t/e name until t/e name fts.>yp/en use i' t/e correct spelling o' t/e 8ord contains a /yp/en :e.g. o91premises

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Logical Rdm Standard