INTRODUCTION TO RELATIONAL DATABASE MANAGEMENT SYSTEM ppsx

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1A.1 Relational Database Desi g n L L E E S S S S O O N N : : 1 1 A A I I N N T T R R O O D D U U C C T T I I O O N N T T O O R R E E L L A A T T I I O O N N A A L L D D A A T T A A B B A A S S E E M M A A N N A A G G E E M M E E N N T T S S Y Y S S T T E E M M O O b b j j e e c c t t i i v v e e s s In this lesson, you will learn to:  Define a Database Management System (DBMS)  Identify the different DBMS users  Describe the need for a database system  Define the architecture of a DBMS in terms of: x External level x Conceptual level x Internal level  Identify the functional components of a DBMS  Identify the need for database planning  Identify the stages in the Database Development Life Cycle (DDLC)  Identify the effects of poor database planning and design 1A.2 Relational Database Desi g n Introduction to Relational Database Management System Lesson 1 / Slide 1 of 12©NIIT Introduction to Relational Database Management System Objectives In this section, you will learn to: • Define a Database Management System (DBMS) • Identify the components of a DBMS • Describe the need for a database system • Define the architecture of a DBMS in terms of: • External level • Conceptual level • Internal level • Identify the functional components of a DBMS • Identify the need for database planning • Identify the stages in the Database Development Life Cycle (DDLC) • Identify the effects of poor database planning and design I I N N S S T T R R U U C C T T O O R R N N O O T T E E S S Lesson Overview The lesson introduces the concept of a database management system (DBMS) and the various users of a DBMS. This lesson also covers the benefits, components, and architecture of a DBMS. In addition, this lesson explains the need for database planning and design and the stages in the database development life cycle. 1A.3 Relational Database Desi g n I I N N T T R R O O D D U U C C T T I I O O N N T T O O D D A A T T A A B B A A S S E E M M A A N N A A G G E E M M E E N N T T S S Y Y S S T T E E M M Introduction to Relational Database Management System Lesson 1 / Slide 2 of 12©NIIT Introduction to Relational Database Management System Introduction to Database Management System • A database is a collection of records. • Database management systems are designed to maintain large volumes of data. • The main objectives of any DBMS are to: • Provide an efficient and convenient environment that is used to store data in and retrieve data from a database. • Manage information about users who interact with the DBMS and the activities that these users can perform on the data. A database is a collection of records. One of the major tasks in a computer system is to store and manage data. To handle this task, you need a specialized computer software known as a Database Management System (DBMS). Database management systems are designed to maintain large volumes of data. Management of data involves: Defining structures for data storage Providing mechanisms for data manipulation Providing data security against unauthorized access Database management systems are now available on a wide range of computers, from desktops to mainframes. The size and power of the computer determine the system facilities, such as security and storage. 1A.4 Relational Database Desi g n A single-user system allows only one person to access a database at any given time. In a multi-user system, several users can access a database simultaneously. With the increasing power of desktop computers, multi-user database systems are now available that support a small group of users to connect to these desktop computers and access data concurrently. These database systems can be scaled up to support hundreds or thousands of users, depending on the configuration of the hardware on which the database system is running. The main objectives of any DBMS are to:  Provide an efficient and convenient environment that is used to store data in, and retrieve data from a database. Manage information about users who interact with the DBMS and the activities that these users can perform on the data. Users Introduction to Relational Database Management System Lesson 1 / Slide 3 of 12©NIIT Introduction to Relational Database Management System Users • There are three types of DBMS users: • Application Programmers: Application programmers write application programs that help an end user to use the database. • End Users: End users interact with a DBMS either by invoking an application program or by writing queries in a database query language. • Database Administrators (DBAs): Database Administrators (DBAs) coordinate the function of collecting information about the data to be stored, and designing and maintaining the database and its security. 1A.5 Relational Database Desi g n A DBMS user can perform the following activities on a database: Add files to the database.  Insert data in the existing files. Retrieve data from the files.  Update data in the files.  Delete data from the files. Remove the existing files from the database. Enforce security and integrity rules. There are three types of DBMS users:  The Application Programmer The End User The Database Administrator (DBA) The Application programmers write application programs that help an end user to use the database. These programs are usually written in languages, such as C, C++, Visual Basic and Visual C++. The programs process data in the database to retrieve, insert, delete, or modify data. End users interact with a DBMS either by invoking an application program or by writing queries in a database query language. The database query language allows the end user to perform basic operations, such as retrieving, deleting, inserting, and updating data. Database Administrators (DBA) coordinate the function of collecting information about the data to be stored, and designing and maintaining the database and its security. The database must be designed and maintained to provide the right information to the authorized people. 1A.6 Relational Database Desi g n I I N N S S T T R R U U C C T T O O R R N N O O T T E E S S Introduction to Database Management System You can give the following additional information about databases: A database is a collection of information organized in such a way that a computer program can quickly select the desired data. You can think of a database as an electronic filing system. Traditional databases are organized by fields, records, and files. A field is a single unit of information; a record is one complete set of fields; and a file is a collection of records. For example, a telephone book is analogous to a file. It contains a list of records, each of which consists of three fields: name, address, and telephone number. Before you list the activities that a user can perform on a database, ask the students what according to them are these possible activities. This will make the session interactive and force the students to think. 1A.7 Relational Database Desi g n W W H H Y Y U U S S E E A A D D A A T T A A B B A A S S E E M M A A N N A A G G E E M M E E N N T T S S Y Y S S T T E E M M ? ? Introduction to Relational Database Management System Lesson 1 / Slide 4 of 12©NIIT Introduction to Relational Database Management System Why use a Database Management System? • The conventional approach to database processing has the following drawbacks: • Duplication of data • Inconsistent data • Some benefits of the database approach are: • Redundancy is reduced • Inconsistency is avoided • Data is shared • Standards are enforced • Security restrictions are applied • Integrity is maintained Before the advent of database management systems, the conventional approach to data processing was followed. In the conventional approach, a program (or a set of programs) is developed for each application. This results in one or more data files for each application. Some of the data may be common between files. However, one application may require the file to be arranged on a particular field, while another application may require the file to be arranged on another field. A major drawback of the conventional method is that the storage and access techniques are built into the programs. Therefore, though the same data may be required by two applications, the data is stored in two different places because each application requires different data storage. 1A.8 Relational Database Desi g n For example, consider the scenario of a university. Association Between Application and Data Files A university typically needs to record certain data about its courses, the students who take the courses, the semesters when the courses are offered, and the instructors who teach the courses. Therefore, the university needs to record data for COURSE, STUDENT, INSTRUCTOR, and SEMESTER. The course scheduling application requires data from the course data file and the student data file. The student admission application requires data from the student data file. For the course scheduling application, the data in the student data file is arranged according to the course code selected by the student. In the student admission application, the data in the student file is arranged on the date of registration of the student. Therefore, though the same data file was required by multiple applications, it had to be duplicated and stored at multiple locations so that each application could access the file. The conventional approach to database processing has the following drawbacks: Duplication of Data: The course data file contains information about various courses. The information includes course code, course name, course description etc. This information is required by the instructors’ schedules application and the semester planning application. In other words, the same data is required by multiple applications. But instead of storing this information in one file, separate files are used by different applications. This repetition of data is referred to as data redundancy. 1A.9 Relational Database Desi g n Inconsistent Data: Because the same data is stored in different places, inconsistency creeps in. For example, the student admission application adds ten students to the student data file. The data of these ten students have to be updated in the student data file used by the course scheduling application. If this change is not made in all files, the university will have inconsistent data in different files. Benefits of the Database Approach Database Approach A major advantage that the database approach has over the conventional approach is that a database management system provides centralized control of data. Following are some of the benefits of the database approach: Redundancy is reduced: In the database approach, applications do not have to maintain their own data files. The same course data file is used by the course scheduling application, the instructor scheduling application, and the semester planning application.  Inconsistency is avoided: Because redundancy is reduced, inconsistency is also avoided. Consider a situation where ten students have enrolled for a course. This information is stored in the student data file. The other applications will use the same student file and therefore, no inconsistency can occur. If this information is recorded in more than one place, inconsistency can occur, as changes made in one data file may not get reflected in another data file. 1A.10 Relational Database Desi g n Data is shared: While the existing applications can share data in the database, new applications can also be developed that will use the same database. Standards are enforced: With centralized control of data, the DBA can ensure that standards are maintained in stored data formats. This is particularly useful for data interchange, or migration of data between two systems.  Security restrictions are applied: The DBA ensures that only authorized persons have access to the database. The DBA defines the security checks to be carried out. Different checks can be applied to different operations on the same data. For instance, a person may have access to query a file, but may not have the right to delete or update that file. Integrity is maintained: Inconsistency between two entries can lead to integrity problems. Even without redundancy, the database can still be inconsistent. For example, a student enrolls in 10 courses when the maximum number of courses a student can enroll in is seven. Or, a student enrolls in a course that is not being offered in that semester. Such problems can be avoided in a DBMS by establishing certain integrity checks that are performed with any update operation. I I N N S S T T R R U U C C T T O O R R N N O O T T E E S S Why use a Database Management System? First, ask the students the following question to make them think about the conventional approach of data processing. What according to you are the features of the conventional approach of data processing? Can you give some examples? Then, explain the conventional approach and its disadvantages. [...]... A DATABASE MANAGEMENT SYSTEM Introduction to Relational Database Management System Architecture of a Database Management System • • • ©NIIT The architecture of a database management system can be broadly divided into three levels: • External level: It is also called the user view This view describes only a part of the actual database • Conceptual level: The conceptual level represents the entire database. .. these users can perform on the data • The users of a DBMS can be broadly classified into application programmers, end-users, and database administrators (DBA) ©NIIT 1A.25 Introduction to Relational Database Management System Relational Database Design Lesson 1 / Slide 1 of 12 Introduction to Relational Database Management System Summary (Contd ) • • • ©NIIT A DBMS provides the following benefits: • Reduced... Integrity The database architecture consists of the external level, the conceptual level, and the internal level The functional components of a DBMS are: • Database manager • File manager • Disk manager Introduction to Relational Database Management System Relational Database Design Lesson 1 / Slide 11 of 12 1A.26 Introduction to Relational Database Management System Summary (Contd ) • • • ©NIIT Database. .. database is visible to the user? 2 Which three subordinate languages constitute the query language? 3 The physical storage of data is described at which level? Solutions 1 External view 2 DDL, DML, and DCL 3 Internal level Relational Database Design 1A.14 FUNCTIONAL COMPONENTS OF A DATABASE MANAGEMENT SYSTEM Introduction to Relational Database Management System Functional Components of a Database Management. .. all the physical input and output Introduction to Relational Database Management System Lesson 1 / Slide 6 of 12 A database management system comprises many modules each dealing with a specific responsibility of the overall system The functional components of a database management system are: The database manager The file manager The disk manager Database Manager The database manager is the central software... stored in the data dictionary 1A.17 Relational Database Design DATABASE DESIGNING AND PLANNING Introduction to Relational Database Management System Database Designing and Planning • • ©NIIT Database planning is a strategic process of finding out the information needs of an organization for an extended period in the future The advantages of database planning are: • It gives a clear picture of the management s... eventually fail Introduction to Relational Database Management System Lesson 1 / Slide 9 of 12 If you do not give ample amount of time and effort to database planning and design, the database can eventually fail The main reasons of database failure are as follows: The key employees who will be using the database are left out from the planning and design process The database collects too much or too little... be the causes Relational Database Design 1A.24 SUMMARY Introduction to Relational Database Management System Summary In this lesson, you learned that: • A DBMS is a collection of interrelated data and a set of programs to access this data • The main objectives of any DBMS are to: • Provide an efficient and convenient environment that is used to store data in and retrieve data from a database • Manage... detailed conceptual model to the implementation model of the DBMS • Database evaluation and maintenance: This stage involves evaluating the performance of the implemented database Introduction to Relational Database Management System Lesson 1 / Slide 8 of 12 You need to follow a process for designing and implementing databases for an organization This process is referred to as the Database Development Life... university The instructor is concerned with only a portion of database that is relevant to the instructor and the administrator is concerned with only the portion of database that is relevant to the administrator These portions of the database, which are viewed, by the instructor and administrator are referred as their user’s view or external view Each user uses a language to carry out database operations . Desi g n I I N N T T R R O O D D U U C C T T I I O O N N T T O O D D A A T T A A B B A A S S E E M M A A N N A A G G E E M M E E N N T T S S Y Y S S T T E E M M Introduction to Relational Database Management System Lesson 1 / Slide 2 of 12©NIIT Introduction to Relational Database Management System Introduction to Database Management System • A database. Desi g n W W H H Y Y U U S S E E A A D D A A T T A A B B A A S S E E M M A A N N A A G G E E M M E E N N T T S S Y Y S S T T E E M M ? ? Introduction to Relational Database Management System Lesson 1 / Slide 4 of 12©NIIT Introduction to Relational Database Management System Why use a Database Management System? • The. Desi g n F F U U N N C C T T I I O O N N A A L L C C O O M M P P O O N N E E N N T T S S O O F F A A D D A A T T A A B B A A S S E E M M A A N N A A G G E E M M E E N N T T S S Y Y S S T T E E M M Introduction to Relational Database Management System Lesson 1 / Slide 6 of 12©NIIT Introduction to Relational Database Management System Functional Components of a Database Management System • The
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