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* * * * * * * * When Not To Use a DBMS Disadvantages Of DBMS: High initial investment in hardware, software, and training. – PowerPoint PPT presentation

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Title: Welcome to ???304


1
??? ???? ?????? ??????
2
Lecture (1)
3
Welcome
  • Welcome to ???304
  • An Introduction to databases.
  • We hope you will enjoy it.

4
Information about course
  • ??? ?????? ????? ????? ???????? An
    Introduction to databases
  • ??? ?????? ???304

5
Database course - People
  • ??????? ?.????? ???? ?????.
  • Office hours sunday 10-2.
  • Email ekambal_at_uofk.edu.
  • ?????? ???????

6
Cont.
  • ??? ???????
  • ?????? ????? ??????? ???? ????? ??? ?????? ? ???
    ???????? ?????? .

????? ?????? 60 ???????? ??????? 15 ????????
??? ?????? 25 ???????????
7
??????? ??????
  • ??????? ????? ???? ??????? ????? ????? ????? ???
    ????? ????????.

8
????? ??????
  • ?????? ??? ????? ???????? ?????? ??????? ???
    ??????? ??? ????? ???????? ????? ?? ?????
    ????????? ??????? ?? ????? ????? ????? ??????
    ????? ????? ????? ????? ? ?????? ??? ???? ?????
    ??? ????? ????????.

9
??????? ?????????
  • ?????? ???????
  • Elmasri and Shamkant. "Fundamentals of Database
    Systems".
  • 5th edition.
  • ???? ?????
  • Thomas M. Connolly Carolyn E.Begg"DataBase
    Systems,A practical Approach To Design
    ,Implementation ,And Management .

    Second Edition.
  • Two references are published by Addison Wesley .

10
Database Systems in two words
  • This course is an introduction to database
    systems
  • Considers questions how to design, implement and
    use data intensive computer applications.
  • Majority of the practical tasks in industry
    require applying relatively not complex
    algorithms to huge amounts of well structured
    data.Accordingly, efficiency of an application
    depends on the quality of (logical and physical)
    data organization.

11
Why Learn Database Systems
  • Wherever you go, there are databases
  • Student records
  • Airlines and hotels reservations,
  • Bank accounts
  • One of the first things people will ask you in an
    job interview is
  • What do you know about databases?
  • Databases are a matured area with a sound
    theoretical foundation and great practical
    knowledge.

12
??????? ??????
  • 1. ???????? ?????? ?????? ???????? ???????? ?????
    ????????
  • Chapter (1)Databases and Database Users
  • 1.1 Introduction.
  • 1.2 An example.
  • 1.3 Characteristics of Database Approach.
  • 1.4 Actors on the Scene.
  • 1.5 Workers behind the Scene
  • 1.6 Advantages of using a DBMS
  • 1.7 A Brief History of DB Application
  • 1.8 When Not to Use a DBMS

13
Cont.
  • 2.?????? ??? ????? ???????? ??????????
  • Chapter(2) Database Systems Concepts and
    Architecture
  • 2.1Data Models, Schemas, and Instances.
  • 2.2Three-schema Architecture and Data
    Independence.
  • 2.3 Database Languages and Interfaces.
  • 2.4 The Database system environment
  • 2.5 Centralized and Client /Server Architecture
    for DBMSs.
  • 2.6 Classification of Database Management Systems

14
Cont.
  • 3. ????? ???????? ????????
  • Chapter(3) Data Modeling Using The Entity
    Relationship (ER) Model.
  • 3.1 Using High-Level Conceptual Data Models for
    Database Design.
  • 3.2 An Example Database Application
  • 3.3 Entity Types, Entity Sets, Attributes, and
    Keys.
  • 3.4 Relationships, Relationship Types, Roles,
    and Structural Constraints.
  • 3.5 Weak Entity Types.
  • 3.6 Refining the ER Design for the COMPANY
    Database.
  • 3.7 ER Diagrams, Naming Conventions, and Design
    Issues.
  • 3.9 Relationship Types of degree higher than two.

15
Cont.
  • 4 ????? ???????? ???????? ??????.
  • Chapter(4) Enhanced Entity Relationship(EER)
    Model.

16
Cont.
  • 5.??????? ????????
  • Chapter(5) Relational data Model and Relational
    Constraints.
  • . 5.1 Relational Data Model Concepts
  • 5.2 Relational Constraints and Relational
    Database .Schemas
  • 5.3 Update Operations ,transaction ,and Dealing
    with Constraints Violations

17
6 ????? ???????? Chapter(6) the Relational
Algebra AND relational calculus
  • 6.1 Unary Relational Operations.
  • 6.2 Relational Algebra Operations from set
    theory.
  • 6.3 binary Relational Operations .
  • 6.6 The Tuple Relational calculus.
  • 6.7 the Domain Relational Calculus.

18
cont.
  • 7. ????? ????? ???????? ??? ??????? ????????
  • Chapter (7) ER to Relational Mapping.
  • 7.1 Relational DB Design Using ER to-
    Relational Mapping.
  • 7.2 Mapping EER Model Constructs to Relation.

19
cont.
  • 8. ??? ??????????? ????????
  • Chapter (8) Structured Query Language
    SQL-99schema Definition, constraints , queries,
    and views.
  • 8.1 SQL Data Definitions , Constraints and data
    types
  • 8.2 Specifying Constraints In SQL.
  • 8.3 schema change statements in SQL.
  • 8.4 Basic Queries in SQL.
  • 8.5 More Complex SQL Queries.
  • 8.6 Insert . Delete , And Update Statements In
    SQL.
  • 8.8 Views (Virtual Table) In SQL.

20
Cont.
  • 9. ???????? ?????? ????????
  • Chapter(10)Functional Dependencies and
    Normalization for relational Databases.
  • 10.1 Informal Design Guidelines for Relation
    Schemas.
  • 10.2 Functional Dependencies.
  • .10.3 Normal forms Based on Primary Keys
  • 10.4 General Definitions of Second and Third
    Normal Forms.

21
??? ???? ?????? ??????
22
Lecture(2) Chapter 1
  • Introduction Databases and Database Users

23
Introduction
  • ?????? ??? ????? ???????? ?? ???? ?????????
    ???????? ??????? , ????????? ?????????,?????
    ????? ?????,???????..........???
  • (databases plays a critical rule in almost all
    areas where computers are used ,including
    business ,ecommerce, engineering, medicine,etc)
  • ????????? ????????? ???? ????? ???????? ????????
    ??? ???? text)) ??????? numbers)).
  • ????? ????????? ??????? ???? ????? ????????
  • Multimedia DB systems
  • Geographical information system (GIS)
  • Data Warehousing And Data Mining
  • Interaction Between DB And WWW
  • Real time and Active DBs
  • Temporal DBs
  • First part of book focuses on traditional
    applications.
  • A number of recent applications are described
    later in the book (for example, Chapters
    24,26,28,29,30)

24
General concepts
  • Definition of DB collection of related data.
  • )????? ???????? ?? ????? ?? ?????? ?? ????????
    ??? ??????? ?????? ?????(.
  • this defn is more general.
  • Essential database characteristics are
  • Represents an aspect of the real world
    (miniworld, UoD),
  • Well structured (even has a strict regular
    structure),
  • Reflects (or should reflect) current state of the
    UoD,
  • Has users and applications,
  • Stored in a permanent (persistent) computer
    memory, and
  • Accessed and manipulated using a DBMS
  • All these characteristics have to be met
  • UOD universe of discourse
  • Mini-world
  • Some part of the real world about which data is
    stored in a database.

25
What Is a Database?
Real World
Facts about world and behaviour of
world represented in contents and operations of a
database
Student Student Student Student
LName FName StudId Major
Ahmed Amna 04-12 Comp
Ali Osman 02-34 Math
A/ Alla Esraa 06-20 Stat
Users
Database
26
  • Another definition A DB is a shared collection
    of logically related data (and description of
    this data ),designed to meet the information
    needs of an organization.

27
Definition of Data (Datum)
  • Data is a value of a property of an individual
    UoD object or a relationship (between two UoD
    objects) at a particular period of time.
  • Example

UoD object(s) Ali Ali CompSci dep
Property Age Number of Points
Time Feb 2005 Feb 2005
Value 21 240
28
  • Another def of data
  • Data
  • Known facts that can be recorded and have an
    implicit meaning
  • A database can be of any size and complexity, and
    it may be generated manually or computerized.

29
Database Management System (DBMS) ??? ????? ?????
????????
  • A collection of programs that enable
  • Defining (describing the structure),
  • Constructing (populating by data),
  • Manipulating (querying, updating),
  • Preserving consistency,
  • Protecting from misuse,
  • Recovering from failure, and
  • Concurrent using
  • of a database.

30
Another definition
  • DBMS A software system that enables users to
    define ,create, maintain the database and
    provides controlled access to this database.
  • DBMS either general purpose or specific purpose
    software.

31
Database systems ??? ????? ????????
  • DBDBMS DB system

Database System The DBMS software together with
the data itself. Sometimes, the applications are
also included.
32
Example of DB
33
Example of DB
  • Mini-world for the example
  • Part of a UNIVERSITY environment.
  • Some mini-world entities
  • STUDENTs
  • COURSEs
  • SECTIONs (of COURSEs)
  • (academic) DEPARTMENTs
  • INSTRUCTORs

34
Example of DB
  • Some mini-world relationships
  • SECTIONs are of specific COURSEs
  • STUDENTs take SECTIONs
  • COURSEs have prerequisite COURSEs
  • INSTRUCTORs teach SECTIONs
  • COURSEs are offered by DEPARTMENTs
  • STUDENTs major in DEPARTMENTs

35
Characteristics of the DB approach
  • Difference between DB systems(DB approach) and
    file-based systems (traditional file processing).
  • Definition of file-based system A collection of
    application programs that perform services for
    the end-users such as production of reports. Each
    program defines and manages its own data.

36
An example of file based system
File definition
37
  • ???? ???? ??? ??????? ??????????
  • Separation and isolation of data.
  • Duplication of data.
  • Data dependence.
  • Incompatibility of files.
  • Fixed queries.

38
DB Approach
  • Arose because
  • Definition of data was embedded in application
    programs, rather than being stored separately and
    independently.
  • No control over access and manipulation of data
    beyond that imposed by application programs.
  • Result
  • the database and Database Management System
    (DBMS).

39
DB Approach
DB SYSTEM
Academic office
DB
Academic application programs
Academic office files and account office files
and files defn
DBMAS
Data entry and reports
Account office
Account application programs
40
Comparison between DB approach and TFP approach
  • The main characteristics of DB approach versus
    TFP approach are
  • Self-Describing Nature of a Database System
  • In addition to DB ,DB system has a
    complete definition or description of the
    database structure and constraints.
  • DB definition is stored in the system catalog,
    which contains information such as the structure
    of each file, the type and storage format of each
    data item, and various constraints on the data.
  • This allows the DBMS software to work with
    different database applications.
  • (Fig 1.1).
  • In TFP .data defn is a part of application
    program , ie these programs are constrained to
    work with only on DB.

41
An example of a database catalog
42
Cont.
  • Insulation between Programs and Data
  • Called program-data independence.
  • Allows changing data structures and storage
    organization without having to change the DBMS
    access programs.
  • The structure of data files is stored in the
    DBMS catalog separately from the access programs.
  • In TFP changes the structure of file may require
    changing all access programs.

43
Cont.
  • Data Abstraction A data model is used to hide
    storage details and present the users with a
    conceptual view of the database.
  • Support of Multiple Views of the Data - Each
    users may see a different view of the database,
    which describes only the data of interest to that
    user. (fig 1.5)

44
(No Transcript)
45
Cont.
  • Sharing of data and multi-user transaction
    processing
  • Allowing a set of concurrent users to retrieve
    from and to update the database.
  • Concurrency control within the DBMS guarantees
    that each transaction is correctly executed or
    aborted.
  • Recovery subsystem ensures each completed
    transaction has its effect permanently recorded
    in the database.
  • OLTP (Online Transaction Processing) is a major
    part of database applications. This allows
    hundreds of concurrent transactions to execute
    per second.

46
??? ???? ?????? ??????
47
Lecture(3) Chapter 1
  • Introduction Databases and Database Users

48
Database Users
  • Users may be divided into
  • Those who actually use and control the database
    content, and those who design, develop and
    maintain database applications (called Actors on
    the Scene), and
  • Those who design and develop the DBMS software
    and related tools, and the computer systems
    operators (called Workers Behind the Scene).

49
Actors on the Scene
  • Database administrator (DBA)
  • 1-Administering the primary resource of DBsystem
    (DB itself) and DBMS (secondary resource).
  • 2- responsible for authorizing access to the db,
    for coordinating and monitoring its use.
  • 3- responsible for acquiring software and
    hardware when needed.
  • 4-Solving the problems of the system such as
    security or poor system response time.

50
Cont.
  • DB designers
  • Responsible to define the content, the
    structure, the constraints, and functions or
    transactions against the database. They must
    communicate with the end-users and understand
    their needs.
  • .

51
Categories of End-users
  • End users - people whose jobs require access to
    the database for querying, updating, and
    generating reports.
  • There are several categories of end users
  • Casual end users (not formal) access db from
    time to time (like managers)
  • Naive or Parametric they make up a large section
    of the end-user population.
  • They use previously well-defined functions in the
    form of canned transactions against the
    database.
  • Examples are bank-tellers or reservation clerks.

52
Categories of End-users (continued)
  • Sophisticated
  • These include business analysts, scientists,
    engineers, others thoroughly familiar with the
    system capabilities.
  • Many use tools in the form of software packages
    that work closely with the stored database.
  • Stand-alone
  • Mostly maintain personal databases using
    ready-to-use packaged applications.
  • An example is a tax program user that creates its
    own internal database.

53
Cont.
  • System Analysts and Application Programmers
    (Software Engineers) - System analysts determine
    the requirements of end users, and develop
    specifications for transactions. Application
    programmers implement these specifications and
    programs. Such analysts and programmers nowadays
    called software engineers.
  •  read section 1.5.

54
Advantages of using DBMS
  • Controlling redundancy
  • redundancy means that storing the same data
    multiple times in the DB.
  • Redundancy problems
  • 1-Duplication of efforts.
  • 2-storage space is wasting
  • 3-Inconsistency of data
  • In DB approach store each logical data item
    (such as a student's name) in only one place.
  • In some cases redundancy is necessary to improve
    system performance and DBMS has capability to
    control such redundancy. FIGURE(1.6)

55
(No Transcript)
56
Cont.
  • Restricting Unauthorized Access-
  • the DBA uses security and authorization subsystem
    (provided by DBMS) in order to specify account
    restrictions.
  • Providing Persistent Storage for Program Objects
    and Data Structures. Compatibility between ODBMS
    (object store) and OOPL(C,JAVA).
  • Permitting Inferencing and actions Using Rules -
  • capability for defining deduction rules for
    inferencing new information from the stored
    database facts. (active DB system ).

57
CONT.
  • Providing Storage Structures For Efficient Query
    Processing
  • DB is stored on disk, so DBMS must provide
    specialized data structures to speed up disk
    search.
  • DBMS often has a buffering module that maintains
    parts of the DB in memory buffers.
  • Query processing and optimization module of the
    DBMS is responsible for choosing an efficient
    query execution plan for each query.
  • Choosing appropriate data structure is a part of
    physical DB design and tuning . (responsibility
    of DBA staff).

58
Cont.
  • Providing Multiple User Interfaces -
  • to satisfy users with varying levels of
    technical knowledge.
  • Interfaces for casual users, form style and menu
    driven (GUIs).
  • Representing Complex Relationships Among Data-
  • A DBMS must have the capability to
    represent a variety of complex relationships
    among the data as well as to retrieve and update
    related data easily and efficiently.

59
Cont.
  • Enforcing Integrity Constraints-
  • capability for defining and enforcing
    constraints
  • (e.g., specifying a data type for each
    data item).
  • Providing Backup and Recovery-
  • A DBMS must provide facilities for
    recovering from hardware or software
    failures.
  • The backup and recovery subsystem o f a
    DBMS is responsible for recovery.

60
Additional Implications of Using the Database
Approach
  • Potential for enforcing standards
  • This is very important for the success of
    database applications in large organizations.
    Standards refer to data item names, display
    formats, screens, report structures, meta-data
    (description of data), Web page layouts, etc.
  • Reduced application development time
  • Incremental time to add each new application is
    reduced.

61
Additional Implications of Using the Database
Approach (continued)
  • Flexibility to change data structures
  • Database structure may evolve as new requirements
    are defined.
  • Availability of current information
  • Extremely important for on-line transaction
    systems such as airline, hotel, car reservations.
  • Economies of scale
  • Wasteful overlap of resources and personnel can
    be avoided by consolidating data and applications
    across departments.

62
Historical Development of Database Technology
  • Early Database Applications
  • The Hierarchical and Network Models were
    introduced in mid 1960s and dominated during the
    seventies.
  • A bulk of the worldwide database processing still
    occurs using these models, particularly, the
    hierarchical model.
  • Relational Model based Systems
  • Relational model was originally introduced in
    1970, was heavily researched and experimented
    within IBM Research and several universities.
  • Relational DBMS Products emerged in the early
    1980s.

63
Historical Development of Database Technology
(continued)
  • Object-oriented and emerging applications
  • Object-Oriented Database Management Systems
    (OODBMSs) were introduced in late 1980s and early
    1990s to cater to the need of complex data
    processing in applications.
  • Many relational DBMSs have incorporated object
    database concepts, leading to a new category
    called object-relational DBMSs (ORDBMSs)
  • Extended relational systems add further
    capabilities (e.g. for multimedia data, XML, and
    other data types)

64
Historical Development of Database Technology
(continued)
  • Data on the Web and E-commerce Applications
  • Web contains data in HTML (Hypertext markup
    language) with links among pages.
  • This has given rise to a new set of applications
    and E-commerce is using new standards like XML
    (eXtended Markup Language). (see Ch. 27).
  • Script programming languages such as PHP and
    JavaScript allow generation of dynamic Web pages
    that are partially generated from a database (see
    Ch. 26).
  • Also allow database updates through Web pages.

65
Extending Database Capabilities
  • New functionality is being added to DBMSs in the
    following areas
  • Scientific Applications
  • XML (eXtensible Markup Language)
  • Image Storage and Management
  • Audio and Video Data Management
  • Data Warehousing and Data Mining
  • Spatial Data Management
  • Time Series and Historical Data Management
  • The above gives rise to new research and
    development in incorporating new data types,
    complex data structures, new operations and
    storage and indexing schemes in database systems.

66
When Not To Use a DBMS
  • Disadvantages Of DBMS
  • High initial investment in hardware, software,
    and training.
  • Generality that a DBMS provides for defining and
    processing data.
  • Overhead for providing security, concurrency
    control, recovery, and integrity functions.

67
cont.
  • The following are the situations where the using
    of a DBMS is not suitable-
  • The database and applications are simple, well
    defined, and not expected to change.
  • Real-time requirements for some program may not
    be met because of DBMS overhead.
  • Multiple-user access to data is not required.

68
cont.
  • When no DBMS may suffice
  • If the database system is not able to handle the
    complexity of data because of modeling
    limitations.
  • If the database users need special operations not
    supported by the DBMS.

69
  • Good bye chapter one

70
  • Chapter(2)
  • Database system concepts and architecture.

71
Data Models
  • Database approach provides some level of data
    abstraction by hiding details of data storage.
  • Data Model
  • A set of concepts to describe the structure of a
    database, the operations for manipulating these
    structures, and certain constraints that the
    database should obey
  • (?????? ?? ???????? ?????? ???? ???? ?????
    ????????)
  • Data Model Structure and Constraints
  • Constructs are used to define the database
    structure
  • Constructs typically include elements (and their
    data types) as well as groups of elements (e.g.
    entity, record, table), and relationships among
    such groups
  • Constraints specify some restrictions on valid
    data these constraints must be enforced at all
    times

72
Data Models (continued)
  • Data Model Operations
  • These operations are used for specifying database
    retrievals and updates by referring to the
    constructs of the data model.
  • Operations on the data model may include basic
    model operations (e.g. generic insert, delete,
    update) and user-defined operations (e.g.
    compute_student_gpa, update_inventory)

73
Categories of data model
  1. High-level or conceptual data models
  2. Low-level or physical data models
  3. Representational or implementation data models

74
High-level or conceptual data models
  • ???????? ?? ??? ????? ???? ???? ????????
    ??????(??? ??????? ?? ???????) ???? ?? ???? ???
    ???????? ??????? ?? ???????.
  • Provide concepts that are close to the way many
    users perceive data.
  • (Also called entity-based or object-based data
    models.)
  • ??? ????? ??? ??????? ?? ?????? ??????? ??????
    ????? ????????.
  • ?????????? ????????((entity relationship model
  • ????? ???????? ?????? enhanced entity
    relationship model ) )

75
Low-level or physical data models
  • ???????? ?? ??? ????? ????? ???? ?? ???????? ??
    ????? ????? ???????? ?? ???????.
  • ???? ??? ???????,????? ??????? ?????? ??????
    ???????
  • ((access paths
  • Provide concepts that describe details of how
    data is stored in the computer. These are usually
    specified in an ad-hoc manner through DBMS design
    and administration manuals
  • ????? unifying model, frame memory

76
Representational or implementation data models
  • ???????? ?? ??? ????? ?? ???? ?????? ????????
    ??????. ???? ?????? ?? ?????? ??????? ? ???? ???
    ???????? ??????? ?? ???????.
  • ?? DBMS ??? ????? ?????? ??? ???.
  • ?????? ?? ??? ??????? ??????? ???? ???????? ???
    ???? ?????
  • (Record-based data models).
  • Provide concepts that fall between the above two,
    used by many commercial DBMS implementations .
  • ?????
  • relational model(?????? ?? ???? ?? DBMS ???????).
  • Hierarchical and network models (?????? ??
    ??????? ???????).
  • Object models(?????? ?? ??ODBMS)

77
Schemas, Instances, and Database State
  • ????? ????? ???????? database schema))??? ?????
    ????????(description of database)
  • Includes descriptions of the database structure,
    data types, and the constraints on the database.
  • ???? ????? ????? ???????? ????? ????? ?????
    ???????? ??? ?????? ?????? ??? ????? .
  • ?? ???? ????? ???????? ???? ??????? ????? ?? ???
    ??????( (diagram
  • Schema Diagram
  • An illustrative display of (most aspects of) a
    database schema.

78
Cont.
  • Schema Construct
  • A component of the schema or an object within the
    schema, e.g., STUDENT, COURSE.

79
Schemas versus Instances
  • Database State
  • The actual data stored in a database at a
    particular moment in time. This includes the
    collection of all the data in the database.
  • ???????? ?? ????? ???????? ?? ???? ?????.
  • Also called database instance (or occurrence or
    snapshot).
  • The term instance is also applied to individual
    database components, e.g. record instance, table
    instance, entity instance.

80
Database Schema vs. Database State
  • Database State
  • Refers to the content of a database at a moment
    in time.
  • Initial Database State
  • Refers to the database state when it is initially
    loaded into the system.
  • Valid State
  • A state that satisfies the structure and
    constraints of the database.
  • ?? DBMS ?????? ?????? ?? ???? ????? ????????
    ?????? ????? (valid state) ???? ???? ??? ?? ???
    ?? ?????? ??????? ??? ???????.

81
Database Schema vs. Database State (continued)
  • Distinction
  • The database schema changes very infrequently.
  • The database state changes every time the
    database is updated.
  • Schema is also called intension.
  • State is also called extension.

82
Example of a Database Schema
83
Example of a database state
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