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APPRECIATE CONCEPT OF DATABASE MANAGEMENT SYSTEM

Data and Information

data are Raw facts and figures.

Processed data is called information. We can take the decision on the base of information. We cannot take the decision on the basis of raw data.

Database: collection of information in form of tables.

Two type of database:

Flat database: all data is stored in a single file e.g. spread sheet

Relational database: all data is stored in multiple tables and tables are linked via common fields. software that handle relational database called RDBMS.

Advantage of database: The database system stores data centrally at one place where all applications can get data required.

Its advantages :

1. Reduce data redundancy

2. Ensure data security

3.Reduce inconsistency

4. Sharing data.

5. enforce standards

NOTE:

Multiple mismatching copies of same data is called data inconsistency

Duplication of data is called data redundancy

Relation: Table is called relation. Every table is collection of records

Tuple: A row or record in a relation is called a tuple.

Attribute(field): A column in a relation is called an attribute. It contain one type of information like name column in stores name of all students in student table

Degree: Number of attributes in a relation is called degree of a relation.

Cardinality: Number of tuples in a relation is called cardinality of a relation.

Primary Key: Primary key is a column that can uniquely identifies the records /tuples in a relation. This key can never be duplicated and NULL.

Composite Primary key: Primary key that composite of two or more columns is called composite Primary key

Candidate Key: Attributes of a table which can serve as a primary key are called candidate keys. Or Primary key and alternate keys together called candidate keys

Alternate Key: All the candidate keys other than the primary key of a relation. Candidate key that is not selected as primary key called alternate key

Foreign Key: Non key attribute of a table acting as primary key in some other table is known as Foreign Key in its current table. This key is used to enforce referential integrity in RDBMS.

RDBMS: relational database management system

It is a software that is used to create and manage relational database.

Well known DBMSs include Base, Microsoft Access, Oracle, MySQL, Microsoft SQL Server and SQLite.

DBA: Data Base Administrator is a person (manager) that is responsible for defining the data base schema, setting security features in database, ensuring proper functioning of the data bases etc./

Database Servers:

Database servers are dedicated computers that hold the actual databases and run only the DBMS and related software.

Database : Collection of information about an organization in form of tables. These tables are logically related with each other

Flat database: all the data is stored in one file then such a database is called Flat Database. A Spreadsheet is an example of flat database

Relational Database: When data is stored in multiple tables that are linked via common filed or column, then such database called Relational database

RDBMS : Relational Database Management System. Software or computer program that manages the relational database effectively and efficiently. E.g MS Access, Base. Oracle, MySQL.

Relation: In RDBMS table is called Relation

Redundancy : duplication of data

Data Inconsistency : Multiple mismatch copy of same data

( .odb) : the file extension of base database is .odb

Components of table:

Data Item/Field/Column/Attribute: Column headers containing one type of information

Record/Row/Tuple: Row in a table . Record contain a complete unit of information.

Primary key: Primary key is a key that can uniquely identifies the records /tuples in a relation. This key can never be duplicated and NULL.

Composite Primary key: Primary key that consist of combination of two or more columns

Alternative keys : The columns that have the unique values for each record but are not selected as the primary keys are called alternative keys

All the candidate keys other than the primary key of a relation

Candidate keys: Primary keys and alternative keys together are called the candidate keys.In other words all attributes that are eligible to be a primary key , are called candidate keys.

This key can never be duplicated and NULL. For example rollno field can be primary key for a table student.

Attributes of a table which can serve as a primary key are called candidate keys.

What is DBMS ?

DBMS is a software program that is used to create and manage databases effectively and efficiently.

The database system stores data centrally at one place where all applications can get data required. Its advantages : 1. Reduce redundancy 2. Enhance data security 3.Reduce inconsistency 4. Sharing data.

Assignment:

Computer based record keeping system called .......
Duplication of data is called.......
Multiple mismatch copies of same data is called .........
A field that uniquely identify record in a table called.........
An interface is user defined layout that lets users can view, view ,enter or change data in tables, know as ...........
Named collection of fields which represent a complete unit of information is called ......
A statement that gives you filtered data according to your condition and specification , is called
A row in a table is called.....
When a primary key contains more than one filed , it is know as...........
........holds a single piece of data.

Ans 1. DBMS 2. data redundancy 3. data inconsistancy 4.Primary key 5. form 6. record 7. Query 8. tuple 9. Comosite primary key 10. Field or attribute or column

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