SQL Server 2005 for Beginners - Fundamentals of DBMS

Fundamentals of DBMS

Data is the most important component in any work we do and it means collection of information. It plays a significant role in the IT landscape as its core function is Information Processing.

A database is an organized collection of data for one or more purposes, usually in digital form.

A database management system (DBMS) is a software package with computer programs that control the creation, maintenance, and use of a database.

It allows users to insert, modify, retrieve and delete the data.

The first databases are existed in the form of files and a file is nothing but collection of records.

A Record is nothing but collection of information or data.

Issue with the File system:

The file system was not so efficient and had many pitfalls.

1)      Security – No User Authentication

2)      Slow Data Search Speed

3)      Data Redundancy – Data Duplication

4)      Data Integrity – Data Validation

5)      Concurrency Control

6)      Slow in Process

File System follows sequential searching process.
 
Types of DBMS or Data Base System Models:

1.       Hierarchical Model

2.       Network Model

3.       Relational Model

Hierarchical Model or HDBMS:

Hierarchical Model is one of the earliest DBMS and here data can be organized in the form of tree structure with one limitation that is “every sub node or child node should have only one parent node”.

Based on the limitation Cross Communication is possible that made this system inefficient.

The below figure depicts the HDBMS:

Network Model or NDBMS:

It was developed to overcome the hurdle of HDBMS. Cross Communication is possible in NDBMS and hence called as ‘Communication Oriented Database Management System’.

It is a complex structure as it has to support cross communication so that we have to write complex programs even for a small operation.

The below figure depicts the NDBMS:

Relational DBMS:

RDBMS is widely accepted database systems in the IT industry today. It was exclusively developed to overcome the drawbacks of HDBMS and NDBMS and used to establish relationship between two-database objects.

The relationship may be:

One to One --- 1:1
One to Many ---- 1: M
Many to One ---- M: 1
Many to Many --- M: M