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DBMS

interface between data and software
foloows ACID (Atomicity,Consistency, Isolation, Durability)

Types of database

Hierachical (tree-like structure)
Network
Relational
Object Oriented

Database Architecture

1-Tier Architecture - database on your machine for instance
2 Tier Architecture - presentaion layer runs on client, data stored on server, end user is not exposed directly
3 Tier Architecture - client-server(application layer)-database

system development life cycle

problem identifcation
analysis
logical ddesign
physical design mapping
implemetation
testing and maintaince

File Based System

Database

Database management system

Database system

Three level / Schema Architecture

External - what user see

Conceptual - logical model

Internal - physical model

ERD - Entity relationship Diagram

Entities - Rectangle
Attributes - Ellipse
Relationship - Diamond

Relational Constrains

Domain Constrains
Key Constrains
Referential Integrity Constrains

operation in Relational Model

Insert
Delete
Modify
Select

Strong Vs Weak Entity