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INTRODUCTION TO DBMS

INTRODUCTION TO DBMS. PRESENTED BY RENUKA AND SUGUNA. INTRODUCTION. In our everyday life in the modern society,we come across databases and database systems quite frequently.

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INTRODUCTION TO DBMS

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  1. INTRODUCTION TO DBMS PRESENTED BY RENUKA AND SUGUNA

  2. INTRODUCTION • In our everyday life in the modern society,we come across databases and database systems quite frequently. • Several activities on a day-to-day basis require the interaction with one or another database. • For example,bank transactions like deposit or withdrawal of money,railway or airline reservation,borrowing or returning a book from a computerized library,purchasing items from a departmental store or through internet,computerized hospital management etc.

  3. TRADITIONAL DATABASE APPLICATIONS • In the traditional database applications,most of the information stored and accessed is either textual or numeric.Some traditional database applications are: • 1Banking • 2Inventory • 3Airline reservation • 4Library management • 5Hospital management

  4. ADVANCED DATABASE APPLICATIONS • Some of the advanced applications of database systems are • 1multimedia database:-That can store pictures,video clips and sound messages. • 2geographical information system(GIS):-That can store and analyze maps,weather data and satellite images. • 3Data warehouses and online analytical processing(OLAP):-That are used in many companies to extract and analyze useful information from very large databases for decesion-making.

  5. ADVANCED DATABASE APPLICATIONS • 4Real-time and active database technology:-That is used in controlling industrial and manufacturing processes. • 5Mobile databases:-They are available on the users portable computers.Users interact with the data stored in the mobile databases through the DBMS • 6Web databases:-Databases are integrated with web to support business operations like “e-commerce”,supply chain management or web publishing. • 7Spatial databases:-provide concepts of databases that keep track of objects in a multidimensional space ex.data in CAD/CAM.

  6. BASICS OF DATABASE TECHNOLOGY • 1 DATA:-Data is a collection of known facts,figures or statistics that can be recorded and that is meaningful.Data can be text,numbers,audio,video or any combination of these.Data in its raw form may not be useful for decision-making.It must be processed so as to become useful. • 2 DATABASE:-It is collection of related data,having valid and implicit meaning and is designed to meet the information needs of an organization.

  7. IMPLICIT PROPERTIES OF DATABASE • A database represents some aspects of the real world.A database has some source from which data is derived. • A data is a logically coherent collection of data with some inherent meaning. • A database is designed,built and populated with data for a specific purpose. • A data can be of any size and any level of complexity. • A database may be generated and maintained manually or by a group of application programs written specifically for that task or by a database management system.

  8. DATABASE MANAGEMENT SYSTEM • A database management system(DBMS)is a collection of programs that enables users to create and maintain a database. • This is a software system that allows access of the data contained in the database. • The primary goal of a DBMS is to provide an environment that is both convenient and efficient to use in storing and retrieving database information.

  9. FUNCTIONS OF DBMS • DBMS is a general purpose software system that performs the following functions. • 1defining a database • 2constructing the database • 3manipulating the database • 4sharing databases among various users • 5protecting the database • 6maintainance of a database

  10. FUNCTIONS OF DBMS • DEFINING A DATABASE:-This involves specifying the data types,structures and constraints for the data to be stored in the database. • CONSTRUCTING THE DATABASE:-This is the process of storing the data on some storage medium that is controlled by DBMS. • MANIPULATING A DATABASE:-This includes functions such as updating the database to reflect changes,querying the database to retrieve specific data,and generating reports from the data.

  11. FUNCTIONS OF DBMS • SHARING A DATABASE:-This function allows multiple users and programs to access the database concurrently i.e. multiple users can use the database simultaneously without creating inconsistent database. • PROTECTION OF DATABASE:-This includes system protection against hardware or software malfunction(or crashes), and security protection against unauthorized or malicious access. • MAINTAINANCE OF DATABASE:-Maintainance of database by the DBMS allows the system to evolve as and when the system requirements change over a period of time.

  12. DATABASE SYSTEM,DBMS CATALOG,META DATA • DATABASE SYSTEM:-The database and the DBMS software together is a database system.It not only contains the database but also a complete definition or description of the database structure and constraints.This definition is stored in what is called the DBMS catalog. • DBMS CATALOG:-The catalog contains the information such as the structure of each file,the type and storage foramat of each data item and various constraints on the data. • META DATA:-The information such as structure of each file,the type and storage format of each data item and constraints on the data stored on the DBMS catalog is called meta-data.Describes the structure of the primary database.

  13. DATABASE SYSTEM

  14. DATABASE SYSTEM ENVIRONMENT • Application programs or queries written by users or programmers • Software to process these queries or application programs • Software to access the stored data • DBMS catalog which contains the stored database definition or metadata • The physical stored database

  15. DATABASE SYSTEM ENVIRONMENT • First the type,structure,constraints for the data specified by the database designer should be stored in the DBMS catalog as stored database definiton(metadata). • This is called defining the database. • The physical location in memory where the database is stored is called stored database.

  16. CHARACTERISTICS OF A DATABASE APPROACH • A single repository of data is maintained in the database approach.This database is defined once and is then accessed by various users. • The main characteristics of the database approach are: • 1self describing nature of a database system • 2program data independence and data abstraction • Support of multiple views of data • Sharing of data and multi-user transaction processing

  17. Self describing nature of the database • In a database approach,the database system contains not only the database also the complete definition of the database. • The definition includes structure of the file,the type and storage format of each data item and is stored in the system catalog. • The information stored in the catalog is referred to as metadata and it describes the structure of the primary database.

  18. Program data independence and data abstraction • In a DBMS environment,if a new field is to be added to the student file,only the student file definition in the catalog has to be changed and no change is needed in the programs that access the database. • This is known as program data independence. • The property that allows program data independence and program operation independence is called data abstraction.

  19. Support of multiple views of data • A database will usually have multiple users,where different users may need different views,different parts of the database. • A view,i.e. the required part may be directly available in the databse(stored)or it may have to be derived from the existing data.

  20. Sharing of data and multi-user transaction processing • In a database approach,a single repository of data is maintained by integrating data from multiple applications. • Different users can share the data from the same database with a multi user DBMS. • It is required that multiple users access the same data at a time.

  21. DIFFERENT PEOPLE BEHIND DBMS • For a small persnoldatabase,a person typically defines,constructs and manipulates the database. • However,many persons are involved in the design,use and maintainance of a large database with a few hundred users. • Their jobs involve the day-to-day use of large database. • There are others who work to maintain the database system environment,but who are not actively interested in the database itself. • There are 2 catagories of people behind DBMS.they are: • 1actors on the scene • 2workers behind the scene

  22. ACTORS ON THE SCENE • The persons involved in the design,use and maintainance of large databases are: • 1 database administrator(DBA) • 2 database designer • 3 end users • 4 software engineer(system analyst and application programmer)

  23. WORKERS BEHIND THE SCENE • The persons who work to mainatin the database environment but are not actively involved in the database itself are: • 1 DBMS system designers and implementers • 2 tool developers • 3 operators and maintainance personnel

  24. ACTORS ON THE SCENE • DATABASE ADMINISTRATOR(DBA):-In a database environment,the primary resource is the database itself and the secondary resource is the DBMS and its related software.In an organization,many users share these resources.Then there arises a need to manage these resources.The DBA is responsible for authorizing access to the database,coordinating and monitoring its use and for acquiring software and hardware resources as needed.

  25. ACTORS ON THE SCENE • DATABASE DESIGNERS:-Database designers are responsible for identifying the data to be stored in the database and for choosing appropriate structure to represent and store this data.It is the responsibility of the database designers to interact with all the end users of the database and understand their requirements and then design the database to fulfill all the user requirements.

  26. ACTORS ON THE SCENE • END USERS:-End users are the people who access the database for querying(retrieving data for a specific requirement),updating and generating reports.There are different catogories of end users.They are: • 1 casual end users • 2 naïve or parametric end users • 3 sophisticated end users • 4 stand alone users

  27. END USERS • CASUAL END USERS:-They are the end users who occasionally access the database. • NAÏVE OR PARAMETRIC END USERS:-Most number of database end users in the naïve or parametric end users.They constantly make use of the databse,querying and updating the database. • SOPHISTICATED END USERS:-They include engineers,scientists,businessanalyst,who thoroughly familiarize with the facilities of DBMS to meet their requirements. • STAND-ALONE USERS:-They maintain personal databases by using readymade packages.These packages provide easy to use menu based or graphics based interfaces.

  28. ACTORS ON THE SCENE • SYSTEM ANALYST AND APPLICATION PRGRAMMERS(SOFTWARE ENGINEERS):-System analyst and application programmers are generally referred to as software engineers.System analysts determine the requirements of end users,especially naïve and parametric users and develop specifications for canned transactions that meet these requirements.

  29. WORKERS BEHIND THE SCENE • DBMS DESIGNERS AND IMPLEMENTERS:-These are the persons who design and implement the DBMS software package and implement it.The DBMS software consists of many complex modules like modules for implementing the catalog,processing query language,processing the interface,accessing and buffering data,controlling concurrency and handling data recovery and security.

  30. WORKERS BEHIND THE SCENE • TOOL DEVELOPERS:-Tools are software packages that facilitate database system design and usage and help in improving perfoemance.Tools include packages for database design,performancemonitoring,graphicalinterfaces,simulation,and test data generation.Tools are optional packages and are often available separately.

  31. WORKERS BEHIND THE SCENE • OPERATORS AND MAINTAINACE PERSONNEL:-These are system administration personnel who are responsible for the actual running and maintainance of the hardware and software environment for the database system.

  32. IMPLICATIONS OF DATABASE APPROACH • The implication of using database approach against the traditional file approach is that,it is beneficial for most organizations.The implications can be listed as follows: • 1 potential for enforcimg standards • 2 reduced application development time • 3 flexibility • 4 availability of up-to-date information

  33. ADVANTAGES OF A USING A DBMS • A good DBMS should posses certain capabilities.With these capabilities,the DBA must acieve a variety of objectives related to the design,administration,and use of a large multi-user database.

  34. ADVANTAGES OF USING A DBMS • 1 controlling redundency • 2 restricting unauthorized access • 3 providing persistent storage for program objects and data structures • 4 providing storage structures for efficient query processing • 5 providing backups and recovery • 6 providing multiple user interfaces • 7 representing complex relationships among data • 8 enforcing integrity constraints • 9 permitting inference and actions using rules

  35. WHEN A DBMS SHOULD NOT USE • DBMS works out costlier under following circumstances: • 1 high initial investment in hardware,software and training • 2 generality that a DBMS provides for defining and processing data • 3 overhead for providing security,concurrencycontrol,recovery and integrity functions. • 4 the database and its applications are simple,well defined and not expected to change • 5 there are stringent real time requirements for some programs that may not be meet because of DBMS overhead. • 6 multiple user access to data is not required.

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