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Database Design Principles – Lecture 1 Database Concepts

Jan 18, 2016

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  • Database Design Principles Lecture 1Database Concepts

  • *Lecture ObjectivesData vs Information Historical Roots of DatabasesWhat is a database, what it does, and why database design is importantWhat a DBMS is, what it does, and how it fits into the database system

  • *Data vs Information Information SystemEncompasses logic, algorithms and dataTransformation of data into useful informationData versus InformationData constitute building blocks of informationInformation produced by processing dataGood, timely, relevant information key to decision makingGood decision making key to organizations survival

  • *Data vs Information

  • *Data vs Information

  • *Historical Roots of DatabasesFirst applications focused on clerical tasksFile systems developed to address needsData organized according to expected useData Processing (DP) specialists computerized manual file systemsRequests for information quickly followedLarge amounts of dataMany users require simultaneous access

  • *Historical Roots of DatabasesOriginal databases applications:Inventory ControlPayrollBankingReservation SystemsNewer database applications:CAD/CAMGPS systems

  • *File System CritiqueFile System Data ManagementRequires extensive programming in third-generation language (3GL)Time consumingMakes ad hoc queries impossibleLeads to islands of information

  • *File System Critique (cont.)Data DependenceChange in files data characteristics requires modification of data access programsMust tell program what to do and howMakes file systems cumbersome from programming and data management viewsStructural DependenceChange in file structure requires modification of related programs

  • *File System Critique (cont.)Field Definitions and Naming ConventionsFlexible record definition anticipates reporting requirementsSelection of proper field names importantAttention to length of field namesUse of unique record identifiers

  • *File System Critique (cont.)Data RedundancyDifferent and conflicting versions of same dataResults of uncontrolled data redundancyData anomaliesModificationInsertionDeletionData inconsistencyLack of data integrity

  • *Introducing the DatabaseData is stored in a database and must be structured and arranged for storage, extraction and processingDatabase consists of a collection of logically related data stored in a single repository which consists of end user data and metadata

  • *Database ManagementA Database Management System (DBMS) manages the access to the database (and ultimately the data)Database Management System (DBMS):Collection of programs that manages database structure and controls access to dataSharing of data among multiple applications and users

  • *Importance of DBMSMakes data management more efficient and effectiveQuery language allows quick answers to ad hoc queriesProvides better access to more and better-managed dataPromotes integrated view of organizations operations Reduces the probability of inconsistent data

  • *DBMS Manages InteractionFigure 1.2

  • *Importance of a DBMSFor Top ManagementProvides the information necessary for strategic decision making and strategic planningProvides access to external and internal dataProvides information on company performance and whether they are achieving their goals (targets)

  • *Importance of a DBMSFor Middle ManagementProvides data necessary for tactical decisions and planningProvides a framework for enforcing and ensuring the security and privacy of the data

  • *Importance of a DBMSFor Operational ManagementProvides timely information for customer supportProduce query results within specified performance levelsRepresents and supports the company operations as closely as possible (operational data)

  • *Database DesignImportance of Good Designeliminates data redundancyeliminates errors leading to bad decisionsPractical ApproachFocus on principles and concepts of database designImportance of logical design

  • *Database vs. File SystemsFigure 1.6

  • *Database System EnvironmentFigure 1.7

  • *DBMS environment rolesDatabase AdministratorsResponsible for:Physical implementation of the DBMSSecurity and integrity control of the DBMSMaintenance of the operational systemEnsuring satisfactory performance of the applications for usersRequires detailed knowledge of the target DBMS and the system environment

  • *DBMS environment rolesDatabase DesignerLogical Database DesignerResponsible for:Identifying the data (entities and attributes)Identifying the relationships between the dataIdentifying the constraints on the dataEnsures that the direction of database development ultimately supports corporate objectives

  • *DBMS environment rolesDatabase DesignerPhysical Database DesignerDecides how the logical database design is to be physically realizedResponsible for:Mapping the logical database design into a set of tables and integrity constraintsSelecting specific storage structures and access methods for the data to achieve good performanceDesigning any security measures required on the data

  • *Database System TypesSingle-user vs. Multiuser DatabaseSingle-user desktopMulti-user workgroupEnterpriseCentralized vs. Distributed

  • *Database UsesProduction or transactionalSupports day-to-day operationsDecision support or data warehouseInformation for tactical or strategic decision makingHistorical Data

  • *DBMS FunctionsData dictionary managementDefines data elements and their relationshipsData storage managementStores data and related data entry forms, report definitions, etcData transformation and presentationTranslates logical requests into commands to physically locate and retrieve the requested data

  • *DBMS FunctionsSecurity managementEnforces user security and data privacy within databaseMulti-user access controlCreates structures that allow multiple users to access the dataBackup and recovery managementProvides backup and data recovery utilities

  • *DBMS FunctionsData integrity managementPromotes and enforces integrity rules to eliminate data integrity problemsDatabase language and application programming interfaces Provides data access through a query languageDatabase communication interfacesAllows database to accept end-user requests within a computer network environment

  • *Where do we go from here?Data Modeling

  • *Where do we go from here?Data Modeling

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