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what is data, information, database, and dbms?

what is data, information, database, and dbms?

Que. what is Data ? Data is a name given to basic facts and Entities. Or Data can be anything Eg. Name , address , etc Attendance sheet where Rollno, name , present or absent Sign are a data.   Que. What is Information ? Meaningful data is known as Information Information helps people in their decision making process. Eg. Merit List ... Read More »

Explain Early Information System or File Processing System

Explain Early Information System or File Processing System

Que. Early Information System(File Processing System) In early days, each business was stores business transactions information in hard copy or in various notebooks. When Computer introduced, each Business transactions information’s were stores in various files. Normally Text file were used to store each information’s and when ever need to Retrieve the information , Application Program were used to retrieve The Information’s. ... Read More »

Data Abstraction Levels OR Explain Data organisation OR View of Data

data abstraction levels

Data Abstraction Levels  OR Explain Data organisation OR View of Data : – A major purpose of a database system, user with an abstract view of data it means the system hides certain parts of how the data are stored and maintain. The data abstraction is a mechanism that hides in a complexity. There are 3 levels of data abstraction, (1) Physical ... Read More »

What is Instance, Schema, and Database Independence?

What is Instance, Schema, and Database Independence?

Que. what is Instance? The collection of information stored in database at a particular moment is called as an instance of the database. Que.  what is Schema? The overall design of the database is called the database schema. The database systems have several schemas partition according to the level of abstraction. 1)      Physical Schema: – It describes the database design at physical level. ... Read More »

Data Models

Data Models

Data Models: – Data model is collection of conceptual tool for describing for data relationship. Data Model is Used to Describe The Overall Data base Schema or Structure. A data model provide a way to describe a design of a database at view level, logical level, and physical level. The data models mainly classified in three categories, (1) Object based Logical ... Read More »

Specialization , Generalization and Aggregation

Generalization specialization

Specialization  Specialization is opposite to Generalization. It is a top-down approach in which one higher level entity can be broken down into two lower level entity. In specialization, some higher level entities may not have lower-level entity sets at all This is a Top-down design process as whown in Figure in which; we designate sub groupings within an entity set that ... Read More »

Components of DBMS

Components of DBMS

   Different components of DBMS are as follows under:- Query language: DDL, DML, DCL, TCL (DBMS language) Query processor or Query language translator Data manager or Storage manage Database users 1. Query language: Query language is the computer language which is used to make a query into database. Query is a statement which is used to requesting & retrieval of ... Read More »

what is Functional Dependency?

what is Functional Dependency?

what is Functional Dependency? A functional dependency is a relationship between two attributes. Typically between the PK and other non-key attributes with in the table.  For any relation R, attribute Y is functionally dependent on attribute X (usually the PK), if for every valid instance of X, that value of X uniquely determines the value of Y. X ———–>      ... Read More »

what is primary key, super key, Candidate Key, Foreign Key, Composite Key, Alternate Key,Secondary Key?

what is primary key, super key, Candidate Key, Foreign Key, Composite Key, Alternate Key,Secondary Key?

(I) Super Key – An attribute or a combination of attribute that is used to identify the records uniquely is known as Super Key. A table can have many Super Keys. E.g. of Super Key  1 ID 2 ID, Name 3 ID, Address 4 ID, Department_ID 5 ID, Salary 6 Name, Address 7 Name, Address, Department_ID ………… So on as any ... Read More »

Normalization in dbms

Normalization in dbms

Normalization is the branch of relational theory providing design insights. The goals of normalization are: be able to characterize the level of redundancy in a relational schema provide mechanisms for transforming schemas to remove redundancy Normalization draws heavily on the theory of functional dependencies. Normalization theory defines six normal forms (NFs). Each normal form involves a set of dependency properties ... Read More »

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