This document provides lecture notes on database management systems, covering topics such as introduction to DBMS, data abstraction, instances and schemas, data models, database design, data storage and querying, transaction management, data mining and information retrieval, and classification of DBMS.
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Lectures Notes in Database Management Systems Lecture (2) Submitted By: Dr. Ahmed Mohamed Abd-Elwahab Lecture in BIS Department, Faculty of Commerce & Business Administration, Helwan University, Cairo, Egypt.
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2 Ch 1. Introduction to DBMS OUTLINE (Part One) ❑Introduction. ❑Basic Definitions. ❑Purpose of Database Systems. ❑Disadvantagesof the File Processing Systems. ❑Main Characteristics (Advantages) of the Database Sy ❑Database Systems Applications.
8 Ch 1. OUTLINE (Part Two) ❑Data Abstraction. ❑Instances and Schemas. ❑Data Models Categories. ❑Database Design. ❑Data Storage and Querying. ❑Transaction Management. ❑Data Mining & Information Retrieval. ❑Classification of DBMS.
9 1.6 Data Abstraction FortheSystemto be usable,itmustretrieve data efficiently.The need for efficiency has leddesigners useComplex data structurestorepresent data database.Since many database systemsusersare no computertrained,developershidetheComplexity from users throughSeveralLevels ofAbstraction,to simplifyUsers'interactions with theSystem. al user mesh sh8l balo b 7aga lma al klam bta3 al mibile yakmle al klam ale ana ktbah
10 Data Abstractionin DBMS is a Processofhidingirrelevant detailsfrom Users.Because database systemsare made of Complex data structures.so,it makesaccessibletheuser interactionwith thedatabase.
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11 1.6 Data Abstraction The Three Levels of Data Abstraction: describe how to storage data nahtm bl data nafsha wl reltion ships
12 1.6 Data Abstraction 1.Physical Level: The Lowest-Level of abstraction describ ➢How thedataare actuallyStored. ➢Complex low-level data structuresin de
13 1.6 Data Abstraction 2.Logical Level: The Next Higher-Level of abstraction des ➢What data are stored in the database. ➢What relationships exist among those data. Database Administrators,who mustdecidewhat information to keep in thedatabase, usethe logical level of abstract consabtion level
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14 1.6 Data Abstraction 3.View level: TheHighest-Levelofabstractiondescribes Only Partof the entire Databaseto simplif interactionbetweenUserswiththeSystem Even though the logicallevelusessimplerstructures,complexity remainsbecauseofthevariety ofinformation stored in a large database.Many usersofthe database system do notneed allthis information; instead, theyneed to access only a part of the data
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16 1.7 Instances and Schemas ❑Instance of the Databaseisthecollection of information storedin thedatabaseata particular moment(Snapshot of the da ❑Database SchemaistheOveralldesign of the database(logical design).Aschemaisa collectionofObjects (Entities)that prov a logical classification of objects in the dat lama aft7 al dolab w abos basa srea ana m7tag ah w mesh m7tag ah w ah ale gwa sora mos8ra
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18 1.7 Instances and Schemas ❑ASchemaisalso anObjectin thedatabase. A database schema can be divided broadly into two categories: 1.Physical Database Schema: Describes the Database Design at thePhysical Level. 2.Logical Database Schema: Describes the Database Design at theLogical Level. 3.Subschema: Describesdifferent views of the Database. entity mesh mhma
19 1.8 Data Models ❑Data Modelisa collection of Conceptua toolsfordescribingdata,relationship between dataandconstraints. ❑DataModelshelpindescribingthe Structure of the Database. quere ya3ne astslam aw astfsar 3n 7aga
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20 1.8 Data Models Categories TheDATA MODELScan be classified int Fourdifferent categories: 1.Relational Model. 2.Entity Relationship Model. 3.Object Based Data Model. 4.Semi Structured Data Model. tables er diagramcolection od entities stucturre ya3ne arkam w 7rof 3wz ta5znhaun structured vedios w oudios ama hana ban al bnan semmi
21 1.Relational Model TheRelationalModelusesacollection of tables =(Relations)to representbothda therelationships among those data. ➢Eachtable(Relation)has multiplecolumns,and eachcolumn has aunique name. ➢TheRelational Modelis an example ofaRecord-Based ➢Record-Based Modelsare so named because the databa structured inFixed-format Records = Tuples = Rows. 1.8 Data Models Categories
22 1.8 Data Models Categories 1.Relational Model Columns = Table = Row = Record
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23 1.8 Data Models categories 2.Entity Relationship Model The Entity Relationship (ER) Data Mode a collection of basic Entities(Objects),and the relationships among these objects. ➢AnEntityis a “thing” or “object” in the real w that is distinguishable from other objects. ➢TheER modelis widely used indatabase desi mesh han2ol relations d 5ls han2ol bdlha entites
24 1.8 Data Models categories 2.Entity Relationship Model
25 3.Object Based Data Model ➢Object Oriented Programming (EspeciallyinJava,C++,orC#)hasbecomethedominant software development methodology. ➢Object Oriented Data Model ExtendingtheE-RmodelwithnotionsofEncapsulation, Methods(functions),Object identity. ➢Combinesfeaturesoftheobject-oriented data model and relational data model. 1.8 Data Models Categories
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26 1.8 Data Models Categories 4.Semi Structured Data Model Specification ofdatawhere individualdata items ofthe same type may havedifferent sets of attributes. ➢Every data item of a particular type must haveth same set of attributes. ➢The Extensible Markup Language(XML) is widely used to representsemi structured data.
27 1.9 Database Design ❑DatabaseSystemsaredesignedto Manage vast amount of data. ❑Database Designmainlyinvolves Design of the Database Schema.
28 1.9 Database Design
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29 1.10 Data Storage and Query The Functional Components of a Database can be broadly divided into theStorage Mana andQuery Processorcomponents. ❑StorageManagerisimportantbecausedatabase typicallyrequirea large amount ofstorage space. ❑Query Managerisimportantbecauseithelpsthe database systemtosimplifyandfacilitateaccess to d
30 1.11 Transaction Managemen Atransactionisa collection of Opera thatPerformsa single logical function database application.
31 1.12 Data Mining & IR ❑Data Mining ➢Isa Processofdiscovering knowledge from dat also calledMachine LearningorStatistical An ➢DMattempts todiscoverrules and patterns from data; “Knowledge discovery in Databases”.
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32 1.12 Data Mining & IR ❑Information Retrieval(IR) ➢Is a Software Program/System thatdeals withthe Organization,Storage,Retrieval,andEvaluationof information from document repositories; “Querying of unstructured textual data”. astrga3 d hya al tare2a ale bn3ml beha kd
33 1.13 Classification of DBMS ❑Database Management Systemscan be Classified based on Several criteria,such as: 1.Data Model, 2.User Numbers, 3.Database Distribution.
34 1.Classification Based on Data Model ➢The most popular data model in use today isRelatio Model.WellknownDBMSslike:Oracle,SQL Server,DB2 andMy SQL. ➢Other traditionalmodels,such as:HierarchicalData Model and Network Data Models. ➢In recentyears,the newerObject-Oriented Data Models were introduced.This model is aDBMSin which information is represented in the form ofObjectsas used inOOP.(OODBMS) combine DB capabilities with OOP language capabilities. 1.13 Classification of DBMS b shkl harme
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35 2.Classification Based on User Number ➢A DBMS can be classification based on thenumber o supports. ❑It can be a Single-User database system, whichsuppone user at a time. ❑Multi-User database system,whichsupportsmultipleusers concurrently. 1.13 Classification of DBMS mknt al atm maslan
36 3.Classification Based on Distribution ➢ThereareFourmain Distributed Systemsfordatabase systems, which can be used to classify the DBMS. 1.Centralized Systems 2.Distributed Database Systems 3.Homogeneous Distributed Database Systems 4.Heterogeneous Distributed Database Systems 1.13 Classification of DBMS data kolha fe mkan wa7d fe mwk3 mo5tlfa kol wa7ed leh dbms
37 Classification Based on Distribution: 1.Centralized Systems: ▪DatabaseandDBMSare stored at aSingle Site is used bySeveral Other Systems. 1.13 Classification of DBMS
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38 Classification Based on Distribution: 2.Distributed Database System: ▪TheactualDatabaseandDBMSaredistributed fromdifferentSitesthatareconnectedbya Computer Network. 1.13 Classification of DBMS matwz3a kol wa7ed leh data base bt3to w dbms
39 Classification Based on Distribution: 3.Homogeneous Distributed Database System ▪Homogeneous Distributed Database Systemsuse theSame DBMSsoftwarefromMultipleSites.Dataexchange between these various sites can behandled easily. 1.13 Classification of DBMS for example libirary information system by the same vendor
40 Classification Based on Distribution: 4.Heterogeneous Distributed Database Syste ▪In aHeterogeneousDistributed Database Systems,different SitesmightusedifferentDBMSSoftware,butthereis additionalcommon softwaretosupportdataexchange between these sites. 1.13 Classification of DBMS ex: the various library data base system use the same machine readable cataloging (MARC) format to support library record data exchange
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