Unit-1.pdf

Course Code : 4040233101 Course Name : DBMS Unit No: 1 SEMESTER: 1 PREPARED BY: Prof. Nidhi Chhangani  CHAPTER 1 TOPIC INTRODUCTION 3 4 5  Purpose of database system It is a collection of tools that enable users to create and manage databas...

Course Code : 4040233101 Course Name : DBMS Unit No: 1 SEMESTER: 1 PREPARED BY: Prof. Nidhi Chhangani  CHAPTER 1 TOPIC INTRODUCTION 3 4 5  Purpose of database system It is a collection of tools that enable users to create and manage databases. In other words, it is general-purpose software that allows users to create, manipulate, and design databases for a number of purposes. Database systems are design to deal with large volumes of data. Data management comprises both the construction of data storage systems and the provision of data manipulation methods. Furthermore, the database system must maintain the security of the information held despite system crashes or attempts at unauthorized access. The system must avoid any unexpected effects if data is to be shared across multiple users. The database applications were built on top of the file system. The goal of a database management system (DBMS) is to transform the following: 1. Data into information. 2. Information into knowledge. 3. Knowledge of the action. 6 7 8  DBMS Architecture The DBMS design depends upon its architecture. The basic client/server architecture is used to deal with a large number of PCs, web servers, database servers and other components that are connected with networks. The client/server architecture consists of many PCs and a workstation which are connected via the network. DBMS architecture depends upon how users are connected to the database to get their request done. 9 1-Tier Architecture In this architecture, the database is directly available to the user. It means the user can directly sit on the DBMS and uses it. Any changes done here will directly be done on the database itself. It doesn't provide a handy tool for end users. The 1-Tier architecture is used for development of the local application, where programmers can directly communicate with the database for the quick response. 10 2-Tier Architecture The 2-Tier architecture is same as basic client-server. In the two-tier architecture, applications on the client end can directly communicate with the database at the server side. For this interaction, API's like: ODBC, JDBC are used. The user interfaces and application programs are run on the client-side. The server side is responsible to provide the functionalities like: query processing and transaction management. To communicate with the DBMS, client-side application establishes a connection with the server side. 11 3-Tier Architecture The 3-Tier architecture contains another layer between the client and server. In this architecture, client can't directly communicate with the server. The application on the client-end interacts with an application server which further communicates with the database system. End user has no idea about the existence of the database beyond the application server. The database also has no idea about any other user beyond the application. The 3-Tier architecture is used in case of large web application. 12 13  DATABASE USERS Database users are categorized based up on their interaction with the database. These are seven types of database users in DBMS. 1. Database Administrator (DBA) : Database Administrator (DBA) is a person/team who defines the schema and also controls the 3 levels of database. The DBA will then create a new account id and password for the user if he/she need to access the database. DBA is also responsible for providing security to the database and he allows only the authorized users to access/modify the database. DBA is responsible for the problems such as security breaches and poor system response time. 1. DBA also monitors the recovery and backup and provide technical support. 2. The DBA has a DBA account in the DBMS which called a system or superuser account. 3. DBA repairs damage caused due to hardware and/or software failures. 4. DBA is the one having privileges to perform DCL (Data Control Language) operations such as GRANT and REVOKE, to allow/restrict a particular user from accessing the database. 14 2. Naive / Parametric End Users : Parametric End Users are the unsophisticated who don’t have any DBMS knowledge but they frequently use the database applications in their daily life to get the desired results. For examples, Railway ticket booking users are naive users. Clerks in any bank is a naive user because they don’t have any DBMS knowledge but they still use the database and perform their given task. 3. System Analyst : System Analyst is a user who analyzes the requirements of parametric end users. They check whether all the requirements of end users are satisfied. 4. Sophisticated Users : Sophisticated users can be engineers, scientists, business analyst, who are familiar with the database. They can develop their own database applications according to their requirement. They don’t write the program code but they interact the database by writing SQL queries directly through the query processor. 5. Database Designers : Database Designers are the users who design the structure of database which includes tables, indexes, views, triggers, stored procedures and constraints which are usually enforced before the database is created or populated with data. He/she controls what data must be stored and how the data items to be related. It is responsibility of Database Designers to understand the requirements of different user groups and then create a design which satisfies the need of all the user groups. 15 6. Application Programmers : Application Programmers also referred as System Analysts or simply Software Engineers, are the back-end programmers who writes the code for the application programs. They are the computer professionals. These programs could be written in Programming languages such as Visual Basic, Developer, C, FORTRAN, COBOL etc. Application programmers design, debug, test, and maintain set of programs called “canned transactions” for the Naive (parametric) users in order to interact with database. 7. Casual Users / Temporary Users : Casual Users are the users who occasionally use/access the database but each time when they access the database they require the new information, for example, Middle or higher level manager. 8.Specialized users : Specialized users are sophisticated users who write specialized database application that does not fit into the traditional data- processing framework. Among these applications are computer aided-design systems, knowledge-base and expert systems etc. 16 17 18 19 20 21 22