Fundamentals of Database System Chapter-1.pptx

Overview of the basic concepts of fundamentals of database

1. Fundamentals of Database Systems ( CoSc2071 ) Chapter One: Introduction to Database System Compiled by: Minychil F. March, 2020 Injibara University Department of Computer Science

2. Introduction Database Databases play a critical role in almost all areas where computers are used, including in business, engineering, medicine, law, education, and library science, etc. Database systems are designed to manage large data set in an organization. They are used to: maintain internal records, present data to customers and clients on the World-Wide-Web, and support many other commercial processes Thus the DB course is about: How to organize data Supporting multiple users Efficient and effective data retrieval Secured and reliable storage of data Maintaining consistent data Making information useful for decision making

3. Definition General definition: A database is a collection of related data in an organized way. Data - facts that can be recorded and that have implicit meaning. e.g. names, telephone numbers, and addresses of the people you know Specific definition: A database is a shard collection of logically related data , organized systematically to meet the information need of multiple users . A random assortment of data cannot correctly be referred to as a database. A database is nothing more than a collection of shared information that exists over a long period of time, often many years. A database represents some aspect of the real world, sometimes called the miniworld or the Universe of Discourse ( UoD ) where Changes to the miniworld can be reflected in the database. A database is designed, built, and populated with data for a specific purpose . It has an intended group of users and some preconceived applications in which these users are interested. It is a collection of data that is managed by a DBMS .

4. Data Handling Approach Data management process passes through the different levels of development along with the development in technology and services. The major three levels are; Manual Approach Traditional File Based Approach Database Approach

5. Database Management levels/approaches …. Manual Approach Primitive and traditional way of information handling Cards and paper are used for the purpose. The data storage and retrieval will be performed using human labour. Files for as many event and objects as the organization are used to store information. Each of the files containing various kinds of information is labelled and stored in one or more cabinets. The cabinets could be kept in safe places for security purpose based on the sensitivity of the information contained in it. Insertion and retrieval is done by searching first for the right cabinet then for the right file then the information. One could have an indexing system to facilitate access to the data

6. Cont… Manual Approach... Limitations of the Manual approach Prone to error Difficult to update, retrieve, integrate You have the data but it is difficult to compile the information Limited to small size information Cross referencing is difficult

7. Cont… An alternative approach of data handling is a computerized way of dealing with the information. The computerized approach could also be either decentralized or centralized based on where the data resides in the system Possible approaches: Traditional File Based Approach (decentralized) Database Approach (centralized)

8. Cont… 2. Traditional File Based Approach File based systems were an early attempt to computerize the manual filing system. This approach is the decentralized computerized data handling method. A collection of application programs perform services for the end-users. In such systems, every application program that provides service to end users define and manage its own data Such systems have number of programs for each of the different applications in the organization. File, in traditional file based approach, is a collection of records which contains logically related data.

9. Cont… 2 . Traditional File Based Approach...

10. Cont… 2 . Traditional File Based Approach Limitations of the Traditional File Based approach Separation or Isolation of Data Limited data sharing Lengthy development and maintenance time Duplication or redundancy of data (money and time cost and loss of data integrity) Data dependency on the application Incompatible file formats or data structures (e.g. “C” and COBOL)

11. Cont… What is a database? A database is a collection of related data in an organized way. Most of the time, Organization is in tabular form. E.g. book database The organization of the database becomes necessary when the data is voluminous. Otherwise, managing data will be very difficult Example A Manufacturing Company with product data A Bank with account data A Hospital with patients A University with Students 3. Database Approach

12. Cont… What is a database system? It is a computerized record keeping system, which stores related data in an organized way. The overall purpose of a database system is to store information and to allow users to add, delete, retrieve, search, query and update that information upon request.

13. Cont … What is a data base management system (DBMS)? A DBMS is software that enables users to define, create, maintain and control access to the database. Example: Ms Access, FoxPro , SQL Server, MySQL , Oracle Ö

14. Characteristics of the Database Approach In the database approach, a single repository of data is maintained that is defined once and then is accessed by various users. The main characteristics of the database approach versus the file-processing approach are the following: Self-describing nature of a database system Insulation between programs and data, and data abstraction Support of multiple views of the data Sharing of data and multiuser transaction processing

15. Cont… Database Approach Database is just a computerized record keeping system or a kind of electronic filing cabinet. Database is a repository/warehouse for collection of computerized data files. Database is a shared collection of logically related data and description of data designed to meet the information needs of an organization. Database is a collection of logically related data where these logically related data comprises entities, attributes, relationships, and business rules of an organization's information. In addition to containing data required by an organization, database also contains a description of the data which is known as “ Metadata ” or “ Data Dictionary ” or “ Systems Catalogue ” or “ Data about Data ”. Database contains information about the data (metadata), it is called a self descriptive collection of integrated records. The purpose of a database is to store information and to allow users to retrieve and update that information on demand. Database is deigned once and used simultaneously by many users. Keeps the data in central position

16. Benefits of the database approach Data can be shared Improved accessibility of data Redundancy can be reduced Quality data can be maintained Inconsistency can be avoided Transaction support can be provided Integrity can be maintained Security measures can be enforced Improved decision support Standards can be enforced Compactness Speed Less labour Centralized information control

17. Cont …

18. Cont … Limitations of Database Approach Introduction of new professional and specialized personnel. Complexity in designing and managing data The cost and risk during conversion from the old to the new system High cost to be incurred to develop and maintain the system Complex backup and recovery services from the users perspective Reduced performance due to centralization and data independency High impact on the system when failure occurs to the central system.

19. Database Management System (DBMS) A software system that enables users to define, create, maintain, and control access to the database. DBMS is a software package used for providing EFFICIENT, CONVENIENT and SAFE MULTI-USER storage of and access to MASSIVE amounts of PERSISTENT data. A DBMS also provides a systematic method for creating, updating, storing, retrieving data in a database. DBMS also provides the service of controlling data access, enforcing data integrity, managing concurrency control, and recovery.

20. Cont … A full scale DBMS should at least have the following services to provide to the user. Data storage, retrieval and update in the database A user accessible catalogue Transaction support service Concurrency Control Services Recovery Services Authorization Services (Security) Support for Data Communication Integrity Services Services to promote data independency between the data and the application Utility services

21. Application program It is a computer program that interacts with the database by issuing an appropriate request (typically an SQL statement) to the DBMS.

22. Components of the DBMS Environment The DBMS environment has five components. Hardware Software Data Procedure People

23. Cont … HARDWARE : Personal computers, mainframe or any server computers to be used in multi-user system, network infrastructure, and other peripherals required in the system. SOFTWARE : They are collection of commands and programs used to manipulate the hardware to perform a function. DBMS software, application programs, operating systems, network software, language software and other relevant software.

24. DATA : The goal of any database system is to have better control of the data and making data useful Data is the most important component to the user of the database. There are two categories of data in any database system: Operational Metadata Operational data is the data actually stored in the system to be used by the user. Metadata is the data about data that is used to store information about the database itself. The structure of the data in the database is called the schema , Schema is composed of the Entities, Properties of entities, and relationship between entities and business constraints . Cont …

25. Cont … PROCEDURE : The rules and regulations on how to design and use a database. It includes procedures like how to logon to the DBMS, how to use facilities, how to start and stop DBMS, how to make backup , how to treat hardware and software failure, how to change the structure of the database & etc .

26. Cont … PEOPLE : It is composed of the people in the organization that are responsible or play a role in designing implementing, managing, administering using the resources in the database. Includes group of people with high level of knowledge about the database and the design technology

27. Actors on the Scene For a small personal database , one person typically defines, constructs, and manipulates the database, and there is no sharing. In large organizations , many people are involved in the design, use, and maintenance of a large database with hundreds or thousands of users. In large organizations, the people whose jobs include the day-to-day use of a large database is known as actors on the scene . Workers behind the scene those who work to maintain the database system environment but who are not actively interested in the database contents as part of their daily job.

28. Cont … There are three actors on the Scene. These are: Database Administrators Database Designers End Users Casual end users Naive or parametric end users Sophisticated end users Standalone users

29. Cont … Database Administrator (DBA) Responsible to oversee, control and manage the database resources (the database itself , the DBMS and other related software) Authorizing access to the database Coordinating and monitoring the use of the database Responsible for determining and acquiring hardware and software resources Accountable for problems like poor security, poor performance of the system Involves in all steps of database development

30. Cont … Database Designer (DBD) Identifies the data to be stored and choose the appropriate structures to represent and store the data. Should understand the user requirement and should choose how the user views the database . Involve on the design phase before the implementation of the database system.

31. Cont … End Users End users are the people whose jobs require access to the database for querying, updating, and generating reports; the database primarily exists for their use. There are several categories of end users: Casual end users Users who access the database occasionally. Need different information from the database each time. Use sophisticated database queries to satisfy their needs. Are most of the time middle to high level managers.

32. Cont … Naive or parametric end users Sizable proportion of users Unaware of the DBMS Only access the database based on their access level and demand Use standard and pre-specified types of queries Sophisticated end users Users familiar with the structure of the Database and facilities of the DBMS. Have complex requirements Have higher level queries Includes engineers , scientists, business analysts, etc Standalone users It maintain personal databases by using ready-made program packages. An example is the user of a financial software package that stores a variety of personal financial data.

33. Cont … Workers behind the scene DBMS designers and implementers : who design and implement different DBMS software. Tool Developers : experts who develop software packages that facilitates database system designing and use. Operators and Maintenance Personnel : system administrators who are responsible for actually running and maintaining the hardware and software of the database system and the information technology facilities.

34. END OF CHAPTER ONE