Database And RDBMS Concept

What is Data?

Data is information converted into binary digital form.

A bit is the smallest unit of data.

Data can be stored in file formats.

Data is represented as video,images, sounds,text etc.

What is Database?

A database is an organized collection of data.

Allows data to be easily accessed, manipulated and updated.

A method of sorting,managing and retriving information.

Modern databases are managed using a database management system (DBMS)

RDMS

RDBMS is a type of DBMS.

Mainitain  the security, accuracy, integrity and consistency.

CRUD

Provide data dictionaries and metadata collections

Data storage management

Structured Query Language(SQL)

Normalization

Process of organizing a database.

Reduce redundancy

Improve data integrity

Simplify database design.

Data in tables and columns

Only related data

Benefits of Normalization

Minimize data redundancy

Minimize null values

Minimize data modification issues

Simplify queries

Cleaner and easier to understand

Speed ,accuracy, and efficiency of the database.

Levels of Normaliation - 1

UNF(Unnormalized Form)

A database is in UNF if it has not been normalized at all.

1NF(First Normal Form)

A releation(table) is in 1NF if (and only if) the domain of each attribute contains only atomic(indivisible) values, and the value of each attribute contains only a single value from that domain.

Levels of Normaliation - 2

2NF(Second Normal Form)

A relation is in 2NF if it is in 1NF and every non-prime attribute of the relation is dependent on the whole of every candidate key.

3NF(Third Normal Form)

A relation is in 3NF if it is in 2NF and every non-prime attribute of the relation is non-transitively dependent on every key of the relation.

Who Needs a Database User

DBA(Database Administrators)

Security Officers

Network Administrator

Application Developers

Application Adminitrators

Users of Application

Responsibilites of DBA

• Install and upgrade
• Allocating system storage
• Creating primary database storage structures
• Creating primary database objects
• Modifying the database structure
• System security
• Backup and Recovery
• User access to the database

Database Objects(Tables)

Attribute/Column

A tupple /Record/ Row

Database Objects(Constraints)

• Not null constraint
• Unique constraint
• Primary key constraint
• Foreigin key constraint
• Check constraint
• REF constraint

Database Objects(Data Types)

Database Objects(Index)

Data structure defined on columns

Speed up data retrieval operations

Small copy of a database table sorted by key values.

Privileges

System privileges

Object privileges

Privilege hierarchy 

The PUBLIC role

Summary

Data

Database

RDMS

Normalization

Database User

Database Objects

Privileges

What is DDL ?

Define the database

Specify data types,structures and constraints

CREATE,ALTER and DROP

Implicitly COMMIT

Connect to Database