Database Management System:

DBMS is a general purpose software system that facilitates the process of defining, constructing, manipulating and sharing databases among various users and applications.

It includes:

1. A modeling language- to define schema(structure) of database.

2. Data Structures- to deal with large amounts of data stored.

3. Database Query Language (Query processing language) which allows users to interactively interrogate the database.

4. Transaction mechanism- that ideally would guarantee the ACID PROPERTIES to ensure data integrity despite concurrent user access and faults.

Key concepts about database:

Field: Smallest piece of information.

Record: Collection of related fields.

File: An organized collection of related records is called a file.

Information:Processed data is called information. 

Database: Collection of related data. It can be of any size and any kind.

Database system = DBMS + Database + Data Model

Building Blocks of Database.

There are three components that form the building block of database.

1. Column’s or Fields or attribute

2. Row or instance or record

3. Table

Characteristics of a Database.

1. Organized and Related.

2. Shared

3. permanent and persistent.

4. Validity, Integrity, correctness.

5. Security.

6. Consistency.

7. Non Redundancy.

8. Independence.

9. Easily accessible.

10. Recoverable.

11. Flexible to change.

Database represents some aspects of real world sometimes called as mini-world or the UOD (universe of discourse). 

Advantages of database management system:

1.      1.It helps in controlling data redundancy.

2.       2. Restricting unauthorized access.

3.       3. Providing persistent storage for program objects.

4.       4. Providing storage structures and search techniques for efficient         query processing.

5.       5. Providing backup and recovery.

6.       6. Providing multi-user interfaces.

7.       7. Representing complex relationships among data.

8.       8. Enforcing integrity constants.

Disadvantages of database management system:

1.       1. Complexity.

2.        2. Size.

3.       3. Performance.

4.       4. Higher impact of failure.

5.       5. Cost of software

          6.  Cost of conversion.

Data models:

Data model is a description of the organization of the database. Data modeling is used for representing entities and their relationships in a database.

It can be defined as an integrated collection of concepts for describing and manipulation, relationships between data and constraints on the data in an organization. In a database a group of similar information or data which of interest to an organization is called entity and each entity can have a number of characteristics. The characteristics of an entity are called attributes. 

It is the collection of co
ncepts that can be used to describe the structure of a database and provides the necessary means to achieve data abstraction by structure of database we mean the data types relationships and constraints that apply to this data.

Types of database mode: