Rdbms Notes

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RELATIONAL DATABASE MANAGEMENT SYSTEM
UNIT-1
INTRODUCTION:DATA :- Data is a collection of facts, which is in unorganized but they can be organized into useful form. Data is of two types :1.Raw Data :- It is a Data which are collected from different sources and has no meaning. ` 2. Derived Data :- It is a data that are extracted from Raw Data and used for getting useful information. Derived Data is called as INPUTDATA. INPUT DATA is processed to get the OUTPUT data. The OUTPUT DATA is called as INFORMATION. The database today may contain either data or information. The term data and information are closely related. INPUT DATA PROCESSING OUTPUT DATA

Proccessing of data is called Data Proccessing. Proccessing of Data in an electronic device i.e computer is called “Electronic Data Proccessing” Meta data: Data that describe the properties or characteristics of other data. Some of these properties include data definition,data or characteristics of other Data,Data Structures,Rules or constraints. Ex:- Datatype : integer,Character,float… Size :- 9,10,…(size of the field) Constraint :- Primary Key

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DataBase : A Database is a collection of interrelated data.  A DataBase 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 Database can be of any size and of varying complexity DATABASE MANAGEMNT SYSTEM (DBMS) :- DBMS is a collection of programs that enables users to create and maintain a database. The dbms is Hence a general-purpose s/w system that facilitates the process of defining, constructing and manipulating databases for various applications. TRADITIONAL FILE PROCESSING:File:- File is collection of records Record: - Record is collection of field’s data. Fields: - Field is a characteristic of a particular data item. or Data. ex:- Filename :- student Fields:- studno, studname, sub1,sub2,sub3…… Record: - 123, abc, 76, 98, 90… File processing systems are still widely used today, especially for backing up database systems. To be useful for business applications, computers must be able to store, manipulate, and retrieve large files of data. Computer file processing systems were developed for this purpose. As business applications became a more complex, it become evident that traditional file processing systems had a number of short comings and limitations. As a result, these systems have been replaced by database processing systems File processing systems are still widely used today, especially for backing up database systems. File Organization: - Maintenance of the records in a file is called File Organization. Evolution of DBMS:-DBMS were first introduced during the 1960s and have continued to evolve during subsequent decades. 1960s:- Traditional file systems and first database management systems were introduced. 1970s:- Hierarchical and Network data base models also known as first generation DBMS 1980s:- Relational model also known as second generation DBMS.In Relational model, all data are represented in the form of tables. A relatively simple fourth-

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generation language called SQL (for Structured Query Language) is used for data retrieval. 1990s:- Object-Oriented and Object-Relational data model DBMS were developed to overcome the limitations of file processing systems. DISADVANTAGES OF FILE PROCESSING SYSTEMS:1. data Redundancy 2. Sharing of data is Poor 3. inconsistent data 4. enforcement of standards are poor 5. data dependency 6. inflexibility

Users of DBMS:Users are of two types 1) The people whose jobs involve the day to day use of a large database. 2) The people who work to maintain the database system environment. 1. DataBase Administrators: - The DBA is responsible for authorizing access to the database, for coordinating and monitoring its use, and for acquiring software and hardware resources as needed. 2. Database Designers: -...
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