Prelims Coverage for CMDM 2210
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The document discusses three key aspects of data - reality, metadata, and data occurrences. Reality refers to real-world entities like employees or products that an organization collects data about. Metadata is data that provides information about the data, such as its definition and attributes. Data occurrences are the actual stored data values in files. The document outlines some traditional approaches to data management and how databases emerged as a way to centrally manage shared data across an organization.
Prelims Coverage for CMDM 2210
- 2. 2 Three Realms Used toThree Realms Used to Describe DataDescribe Data Reality (Real World)Reality (Real World) Metadata (Data Definition)Metadata (Data Definition) Data (Data Occurences)Data (Data Occurences)
- 3. 3 1. Reality1. Reality It consist of the organizationIt consist of the organization itself, the various componentsitself, the various components of the organization and theof the organization and the environment in which theenvironment in which the organization operates.organization operates.
- 4. 4 EntityEntity Any object or even about whichAny object or even about which the organization chooses tothe organization chooses to collect and store datacollect and store data Ex. Employee, Product,Ex. Employee, Product, Computer or it may be anComputer or it may be an intangible item such as bankintangible item such as bank account, a cost center, a partaccount, a cost center, a part failure or an airline flightfailure or an airline flight
- 5. 5 Entity ClassEntity Class A collection of entities thatA collection of entities that posses similar characteristicsposses similar characteristics Ex. Entity class areEx. Entity class are customers, students andcustomers, students and patientpatient
- 6. 6 AttributeAttribute A property of an entity thatA property of an entity that we choose to record.we choose to record.
- 7. 7 IdentifierIdentifier Unique property of an entityUnique property of an entity
- 8. 8 2. METADATA2. METADATA Information about the dataInformation about the data in organizationin organization Stored and maintained inStored and maintained in the organization’s datathe organization’s data dictionary or directorydictionary or directory
- 9. 9 Data ItemData Item A unit factA unit fact The smallest name unit ofThe smallest name unit of data in a database thereforedata in a database therefore the smallest unit of data thatthe smallest unit of data that has meaning to a userhas meaning to a user Also called as data elements,Also called as data elements, fields or attributesfields or attributes
- 10. 10 Data AggregateData Aggregate A collection of data items thatA collection of data items that is named and referenced as ais named and referenced as a whole.whole.
- 11. 11 RecordRecord A named collections of dataA named collections of data items and/or data aggregatesitems and/or data aggregates Most organization define oneMost organization define one record type for eachrecord type for each entity/classentity/class
- 12. 12 KeyKeyA data item used to identify aA data item used to identify a recordrecord The primary key of a recordThe primary key of a record corresponds to the identifier of acorresponds to the identifier of a real-worldreal-world A secondary key is does notA secondary key is does not uniquely identify a record butuniquely identify a record but identifies a number of records in aidentifies a number of records in a set that share same propertyset that share same property
- 13. 13 3. Data3. Data It consists of occurrencesIt consists of occurrences A file is named collection of allA file is named collection of all occurrences of a given recordoccurrences of a given record typetype A file maybe visualized asA file maybe visualized as two-dimesional called flat filetwo-dimesional called flat file
- 14. 1414 Data HierarchyData Hierarchy The basis for anyThe basis for any information processinginformation processing activity involvingactivity involving databasesdatabases
- 16. 16 BitsBits Binary Digits of 0’s and 1’sBinary Digits of 0’s and 1’s
- 17. 17 CharacterCharacter Represented by a group ofRepresented by a group of bits that are configuredbits that are configured according to an encodingaccording to an encoding system, such as the ASCIIsystem, such as the ASCII Same as ByteSame as Byte Ex. A, 1, E, @Ex. A, 1, E, @
- 18. 18 FieldField The lowest level in the dataThe lowest level in the data hierarchy at which we canhierarchy at which we can derive any meaning from thederive any meaning from the datadata Ex. Last Name, Age, CityEx. Last Name, Age, City
- 19. 19 RecordRecord A description of an event or anA description of an event or an itemitem Group of related fieldsGroup of related fields Ex. Student Record,Ex. Student Record, Employee RecordEmployee Record
- 20. 20 FileFile A collection of related recordsA collection of related records Sorted merged and processedSorted merged and processed by a key fieldby a key field Ex. Personal FileEx. Personal File
- 21. 21 DatabaseDatabase A collection of non-redundantA collection of non-redundant data which can be shared bydata which can be shared by different application systems.different application systems. Ex. Company DatabaseEx. Company Database
- 22. 2222 The TraditionalThe Traditional Approach to DataApproach to Data ManagementManagement - Focuses on the data- Focuses on the data processing needs of individualprocessing needs of individual departments in thedepartments in the organizationorganization
- 23. 23 File Processing SystemFile Processing System Refers to the use of computerRefers to the use of computer files to store data in persistentfiles to store data in persistent memory, wherein the data ismemory, wherein the data is store even after the computerstore even after the computer has been turned off andhas been turned off and restartedrestarted
- 24. 24 Note:Note: File processing is an usefulFile processing is an useful alternative to a database onlyalternative to a database only where the information is onlywhere the information is only going to be accessed by a singlegoing to be accessed by a single user, where speed of data input isuser, where speed of data input is vital and where the amount ofvital and where the amount of data being stored is relativelydata being stored is relatively smallsmall
- 25. 2525 The EmergenceThe Emergence of the Databaseof the Database
- 26. 26 1950s and Early 1960s1950s and Early 1960s Data processing usingData processing using magnetic tapes for storagemagnetic tapes for storage Tapes provide only sequentialTapes provide only sequential accessaccess Punched cards for outputPunched cards for output
- 27. 27 Late 1960s & 1970sLate 1960s & 1970s Hard disk allow direct acces toHard disk allow direct acces to datadata Network and hierarchical dataNetwork and hierarchical data models in widespread usemodels in widespread use High performance transactionHigh performance transaction processingprocessing
- 28. 28 1980s1980s Research relational prototypesResearch relational prototypes evolve into commercial systems.evolve into commercial systems. SQL becomes industrialSQL becomes industrial standardsstandards Parallel and distributed databaseParallel and distributed database systemssystems Object-oriented databaseObject-oriented database systemssystems
- 29. 29 1990s1990s Large decisions support andLarge decisions support and data mining applicationsdata mining applications Large multi-terabyte dataLarge multi-terabyte data warehousewarehouse Emergence of web commerceEmergence of web commerce
- 30. 30 2000s2000s XML and XQUERY standardsXML and XQUERY standards Automated DatabaseAutomated Database AdministrationAdministration
- 31. 3131 DatabaseDatabase ApproachApproach -Represents a different conceptRepresents a different concept in information resourcein information resource managementmanagement - The concept is rooted in anThe concept is rooted in an attitude of sharing commonattitude of sharing common data resourcesdata resources
- 32. 32 ElectronicElectronic SpreadsheetsSpreadsheets Also known as Flat FileAlso known as Flat File DatabasesDatabases Faster than manual database butFaster than manual database but for a large number of entries arefor a large number of entries are very slowvery slow Data is duplicated and oftenData is duplicated and often misfiledmisfiled
- 33. 3333 Advantages of theAdvantages of the DatabaseDatabase ApproachApproach
- 34. 34 1. Program-Data1. Program-Data IndependenceIndependence The data will be held in such aThe data will be held in such a way that if the user make changesway that if the user make changes to the structure of the database,to the structure of the database, the program that access the datathe program that access the data will not be affectedwill not be affected
- 35. 35 2. Data Consistency2. Data Consistency Due to the fact that each dataDue to the fact that each data item is held only once, there isitem is held only once, there is no danger of an item beingno danger of an item being updated on one system andupdated on one system and not on the othernot on the other
- 36. 36 3. Controlled3. Controlled RedundancyRedundancy Reducing to a minimum theReducing to a minimum the number of data items whichnumber of data items which are duplicated in a databaseare duplicated in a database
- 37. 37 4. Data Integrity4. Data Integrity The protection of data fromThe protection of data from accidental, deliberate corruptionaccidental, deliberate corruption or modification in the databaseor modification in the database The ability to specify constraintsThe ability to specify constraints on dataon data
- 38. 38 5. Data Security5. Data Security Only authorize users gain accessOnly authorize users gain access to the datato the data Also to protect the rights ofAlso to protect the rights of individual and organization toindividual and organization to restrict access to informationrestrict access to information which relates to them and is of awhich relates to them and is of a private natureprivate nature
- 39. 39 6. Data Integration6. Data Integration Data are organized into a single,Data are organized into a single, logical structure, with logicallogical structure, with logical relationships defined betweenrelationships defined between associated data entitiesassociated data entities
- 40. 40 7. Data Sharing7. Data Sharing A database is intended to beA database is intended to be shared by all authorized usersshared by all authorized users in the organization.in the organization.
- 41. 41 8. Enforcement of8. Enforcement of StandardStandard Has the authority to define andHas the authority to define and enforce data standards.enforce data standards. All changes to data standardsAll changes to data standards would have to be approved bywould have to be approved by database administrationdatabase administration
- 42. 42 9. Ease of Application9. Ease of Application DevelopmentDevelopment The cost and time forThe cost and time for developing new businessdeveloping new business applications are greatlyapplications are greatly reducedreduced
- 43. 43 10. Data Accessibility10. Data Accessibility and Responsivenessand Responsiveness Provides multiple retrieval pathsProvides multiple retrieval paths to each item of data, giving a userto each item of data, giving a user much greater flexibility in locatingmuch greater flexibility in locating and retrieving data than with dataand retrieving data than with data filesfiles
- 45. 45 1. New, Specialized1. New, Specialized PersonnelPersonnel Need to hire o train individuals toNeed to hire o train individuals to maintain the new databasemaintain the new database software, develop and enforcesoftware, develop and enforce new programming standards tonew programming standards to achieve the highest possibleachieve the highest possible performanceperformance
- 46. 46 2. Need for Explicit2. Need for Explicit BackupBackup Minimal data redundancy, withMinimal data redundancy, with all its associated benefits, alsoall its associated benefits, also may fail to provide backupmay fail to provide backup copies of datacopies of data
- 47. 47 3. Interference with3. Interference with Shared DataShared Data The concurrent access to sharedThe concurrent access to shared data via several applicationdata via several application programs can lead to someprograms can lead to some problemsproblems
- 48. 48 4. Organizational Usage4. Organizational Usage A shared database requires aA shared database requires a consensus on data definitionsconsensus on data definitions and ownership as well asand ownership as well as responsibilities for accurateresponsibilities for accurate data maintenancedata maintenance
- 50. 50 Enterprise DataEnterprise Data ModelModel Graphical model showingGraphical model showing high-level entities andhigh-level entities and relationships for therelationships for the organizationorganization
- 51. 51 Relational DatabaseRelational Database Database technology involvingDatabase technology involving tables (relation) representingtables (relation) representing entities and primary/foreignentities and primary/foreign keys representingkeys representing relationshipsrelationships
- 52. 52 Use of InternalUse of Internal TechnologyTechnology Networks andNetworks and telecommunications, distributedtelecommunications, distributed databases, client server and tierdatabases, client server and tier architecturearchitecture
- 53. 53 DatabaseDatabase ApplicationsApplications Application programs used toApplication programs used to perform activities for databaseperform activities for database usersusers
- 54. 54 The DatabaseThe Database PhilosophyPhilosophy Each piece of information be enteredEach piece of information be entered and stored just onceand stored just once Every authorized user have quick anEvery authorized user have quick an easy access to any of the stored dataeasy access to any of the stored data Data is entered, maintained andData is entered, maintained and access in ways that they are notaccess in ways that they are not dependent on any particulardependent on any particular application programsapplication programs
- 55. 5555 DatabaseDatabase SystemSystem - An integrated system of- An integrated system of computer, hardware,computer, hardware, software and human user.software and human user.
- 56. 56 Components ofComponents of Database EnvironmentDatabase Environment Data Administrator System Developer End User User Interface Application Programs DBMS DatabaseRepositor y