Database Management System

Database:
A database is a organized collection of data. It is the collection of schemas, tables, queries, reports, views and other objects.

Database Management System:
It is a computer software application that interacts with the user, other applications, and the database itself to capture and analyse data. A general-purpose DBMS is designed to allow the definition, creation, querying, update and administration of databases.


Characteristics:

• Real-world entity
• Relation-based tables
• Isolation of data and application
• Less redundancy
• Consistency
• Query Language
• ACID properties
• Multi-user and concurrent access
• Multiple view
• Security

Users:

• Administrators
• Designers
• End Users

Architecture Model:

3-tier model:

1. User (Presentation) tier
2. Application (Middle) tier
3. Database (Data) tier

Data Models:

Entity-Relationship model:

• Entities and their attributes
• Relationships among entities

Mapping cardinalities:

• one to one
• one to many
• many to one
• many to many

Relational Model:

Data schemas:

• Physical data schema
• Logical data schema

Entities and attributes:

Types of attributes:

• Single attribute
• Composite attribute
• Derived attribute
• Single-value attribute
• Multi-value attribute

Entity-set and keys:

• Super key
• Primary key
• Candidate key