A collection of known facts and figures.
May contain text, numbers, images, sounds or
videos etc. It doesn’t convey useful information
Data about data (describes prop and char of other data)
1. Processed form of data is called Information
2. Processed data to increase knowledge of user
e.g Name, Ages Older than 30
* Bit: Smallest unit of data; binary digit (0,1)
* Byte: Group of bits that represents a single character
* Field: Group of words or a complete number
* Record: Group of related fields
* File: Group of records of same type
* Database: Group of related files
A shared collection of logically related data
stored to meet the requirements of different users of an organization SOFTWARE
A set of instructions to perform some specific tasks
to meet the information needs of an org
DATABASE MANAGEMENT SYSTEM
Is a set of computer programs (Software) that is
used to manage the data and the users of data.
FILE MANAGEMENT SYSTEMS:
File Processing System is a collection of programs that perform services for the end-user, such as production of reports and management of data. DISADVANTAGES OF FILE PROCESSING SYSTEM
Data Redundancy means same information is duplicated in several files. This makes data redundancy.
Data Inconsistency means different copies of the same data are not matching. That means different versions of same basic data are existing. This occurs as the result of update operations that are not updating the same data stored at different places. Example: Address Information of a customer is recorded differently in different files.
Difficulty in Accessing Data
It is not easy to retrieve information using a conventional file processing system. Convenient and efficient information retrieval is almost impossible using conventional file processing system.
Data are scattered in various files, and the files may be in different format, writing new application program to retrieve data is difficult. Integrity Problems
The data values may need to satisfy some integrity constraints. For example the balance field Value must be grater than 5000. We have to handle this through program code in file processing systems. But in database we can declare the integrity constraints along with definition itself. Concurrent Access anomalies
If multiple users are updating the same data simultaneously it will result in inconsistent data state. In file processing system it is very difficult to handle this using program code. This results in concurrent access anomalies.
Enforcing Security Constraints in file processing system is very difficult as the application programs are added to the system in an ad-hoc manner. ENTITIES
An entity is an object that exists and is distinguishable from other objects. An entity may be concrete (a person or a book, for example) or abstract. An entity is represented by a set of attributes. ATTRIBUTES
An attribute is a function which maps an entity set into a domain. One can characterize a DBMS as an "attribute management system" where attributes are small chunks of information that describe something. Entity Relationship Diagram
An entity relationship diagram, also called entity relationship model, is a graphical representation of entities and their relationships to each other, typically used in computing in regard to the organization of data within databases or information systems. NORMALIZATION
Normalization is the process of organizing data in a database. This includes creating tables and establishing relationships between those tables according to rules designed both to protect the data and to make the database more flexible by eliminating redundancy and inconsistent dependency.
Redundant data wastes disk space and creates maintenance problems. If data that exists in more than one place must be changed, the data must be...
References: CITY(CTCODE) NOT NULL
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