SQL server, Oracle, MySQL, MariaDB, SQLite.

(i) Data are raw facts stored in a computer. A data may contain any character, text, word or a number.
(ii) Information is formatted data, which allows to be utilized in a significant way.

Database normalization was first proposed by Dr.Edgar F Codd as an integral part of RDBMS in order to reduce data redundancy and improve data integrity. These rules are known as E FCodd Rules.

Hierarichal data Model	Network data model
In Hierarchical model, a child record has only one parent node	In a Network model, a child may have many parent nodes,
It Hierarchical model, data is represented as a simple tree like structure form.	It represents the data in many-to-many lationships.

 

(i) Foxpro
(ii) dbase

Entity Relationship Model (ER model):
(i) In this database mo-ad., relationship are created by dividing the object into entity and its characteristics into attributes.
(ii) It was developed by Chen in 1976. This model is useful in developing a conceptual design for the database.
(iii) It is very simple and easy to design logical view of data. The developer can easily understand the system by looking at ER model constructed.

(i) Hierarchical model was developed by IBM as Information Management System.
(ii) In Hierarchical model, data is represented as a simple tree like structure form. This model represents a one-to-many relationship ie parent-child relationship.
(iii) One child can have only one parent but one parent can have many children. This model is mainly used in IBM Main Frame computers.

Database Administrators:
Database Administrator or DBA is the one who manages the complete database management system. DBA takes care of the security of the DBMS, managing the license keys, managing user accounts and access etc.
Application Programmers or software Developers:
This user group is involved in developing and designing the parts of DBMS.
End User:
All modern applications, web or mobile, store user data. Applications are programmed in such a way that they collect user data and store the data on DBMS systems running on their server. End users are the one who store, retrieve, update and delete data.
Database designers:
Database designers are responsible for identifying the data to be stored in the database for choosing appropriate structures to represent and store the data.

Object model stores the data in the form of objects, attributes and methods, classes and inheritance. This model handles more complex applications, such as Geographic information System (GIS),sdentific experiments, engineering design and manufacturing. It is used in file Management System. It represents real world objects, attributes and behaviors. It provides a clear modular structure. It is easy to maintain and modify the existing code.

An example of the Object model is Shape, Circle, Rectangle and Triangle are all objects in this model
(i) Circle has the attribute radius.
(ii) Rectangle has the attributes length and breadth.
(iii) Triangle has the attributes base and height.
(iv) The objects Circle, Rectangle and. Triangle inherit from the object Shape

Database Administrator or DBA is the one who manages the complete database management system. DBA takes care of the security of the DBMS, managing the license keys, managing user accounts and access etc.

The Database Management System can be divided into five major components as follows:
(i) Hardware
(ii) Software
(iii) Data
(iv) Procedures / Methods
(v) Database Access Languages

(i) Hardware: The computer, hard disk, I/O channels for data, and any other physical component involved in storage of data
(ii) Software: This main component is a program that controls everything. The DBMS software is capable of understanding the Database Access Languages and interprets into database commands for execution.
(iii) Data: It is that resource for which DBMS is designed. DBMS creation is to store and utilize data.
(iv) Procedures/Methods: They are general instructions to use a database management system such as installation of DBMS, manage databases to take backups, report generation, etc
(v) DataBase Access Languages: They are the languages used to write commands to access, insert, update and delete data stored in any database.
Examples of popular DBMS: Dbase, FoxPro

Relational Algebra is divided into various groups
Unary Relational Operations.
(i) SELECT (symbol: σ)
(ii) PROJECT ( symbol: π)
Relational Algebra Operations from Set Theory:
(i) UNION (U)
(ii) INTERSECTION (∩)
(iii) DIFFERENCE (-)
(iv) CARTESIAN PRODUCT (X)
SELECT (symbol: σ)
(i) General from σ (R) with a relation R and a condition C on the attributes of R
(ii) The SELECT operation is used for selecting a subset with tuples according to a given condition.
(iii) Select filters out all tuples that do not satisfy C
STUDENT:

Studio	Name	Course	Year
CS1	Kannan	Big Data	II
CS2	Gowri Shankar	R language	I
CS3	Lenin	Big Data	I
CS4	Padmaja	Python Programming	I

σ course = "Big Data" (STUDENT) 

Studio	Name	Course	Year
CS1	Kannan	Big Data	II
2	Lenin	Big Data	I

PROJECT (symbol: II)
(i) The projection eliminates all attributes of the input relation but those mentioned in the projection list.
(ii) The projection method defines a relation that contains a vertical subset of Relation.
Example: 1
II_course (STUDENT)
Result:

Course

Big Data

R language

Python Programming

Example 2 
II_{student,course} (STUDENT)
Result:

Stud no	Course
CS1	Big Data
CS2	R language
CS3	Big Data
CS4	Python Programming

UNION (Symbol: U)
(i) It includes all tuples that are in tables A or in B. It also eliminates duplicates. Set A Union Set B would be expressed as A U B
Example 3:

Table A
Studio	Name
CS1	Kannan
CS2	Lenin
CS3	Padmaja

Table A
Studio	Name
CS1	Kannan
CS2	Gowrishakaran
CS3	Lenin

Result:

Table A
Studio	Name
CS1	Kannan
CS2	Gowri Shakaran
CS3	Lenin
CS4	Padmaja

SET DIFFERENCE (Symbol: -)
(i) The result of A - B, is a relation which includes all tuples that are in A but not in B.
(ii) The attribute name of A has to match with the attribute name in B.
Example: 4
using Table B Example 3 
Result:

Table A - B
CS4	Padmaja

INTERSECTION (symbol: ∩) A ∩ B:
(i) Defines a relation consisting of a set of all tuple that are in both in A and B. However,  A and.B must be union-compatible.
Example: 5 
Using Table in Example 3
Result:

Table A - B
CS1	Kannan
CS3	Lenin

PRODUCT OR CARTESIAN PRODUCT (Symbol: X)
(i) Cross product is a way of combining two relations. The resulting relation contains, both relations being combined.
(ii) A x B means A times B, where the relation A and B have different attributes.
(iii) This type of operation is helpful to merge columns from two relations.

Basis of Comparison	DBMS	RDBMS
Expansion	Database Management System	Relational Database Management System
Data storage	Navigational model ie data by linked records	Relational model (in tables). ie data in tables as row and column
Data redundancy	Exhibit	Not Present
Normalization	Not performed	RDBMS uses normalization to reduce redundancy
Data access	Consumes more time	Faster, compared to DBMS.
Keys and indexes	Does not use.	used to establish relationship. Keys are used in RDBMS.
Transaction management	Inefficient, Error prone and insecure	Efficient and secure
Distributed Databases	Not supported	Supported by RDBMS.
Example	Dbase, FoxPro.	SQL server, Oracle, mysql, MariaDB, SQLite.

Types of a Data Model:
1. Hierarchical Model
2. Relational Model
3. Network Database Model
4. Entity Relationship Model
5. Object Model.
1. Hierarchical Model:
(i) Hierarchical model was developed by IBM as Information Management System. In Hierarchical model, data is represented as a simple tree like structure form.
(ii) This model represents a one-to-many relationship i.e., parent-child relationship. One child can have only one parent but one parent can have many children.
(iii) This model is mainly used in IBM Main Frame computers.

2. Rational Model:
(i) The Relational Database model was first proposed by E.F. Codd in 1970. Nowadays, it is the most widespread data model used for database applications around the world.
(ii) The basic structure of data in relational model is tables (relations). All the information's related to a particular type is stored in rows of that table.
(iii) Hence tables are also known as relations in a relational model. A relation key is an attribute which uniquely identifies a particular tuple (row in a relation (table)).

3. Network Model:
Network database model is an extended form of hierarchical data model. The difference between hierarchical and Network data model is:
(i) In hierarchical model, a child record has only one parent node,
(ii) In a Network model, a child may have many parent nodes. It represents the data in many-to-many relationships.
(iii) This model is easier and faster to access the data.

(iv) School represents the parent node
(v) Library, Office and Staff room is a child to school (parent node)
(vi) Student is a child to library, office and staff room (one to many relationship)
4. Entity Relationship Model:
(i) In this database model, relationship are created by dividing the object into entity and its characteristics into attributes.
(ii) It was developed by Chen in 1976. This model is useful in developing a conceptual design for the database. It is very simple and easy to design logical view of data. The developer can easily understand the system by looking at ER model constructed.
(iii) Rectangle represents the entities. E.g. Doctor and Patient.
(iv) Ellipse represents the attributes E.g. D-id, D-name, P-id, P-name. Attributes describes the characteristics and each entity becomes a major part of the data stored in the database. Diamond represents the relationship in ER diagrams e.g; Doctor diagnosis the Patient.

5. Object Model:
(i) Object model stores the data in the form of objects, attributes and methods, classes and Inheritance.
(ii) This model handles more complex applications, such as Geographic information System (GIS), scientific experiments, engineering design and manufacturing.
(iii) It is used in file Management System. It represents real world objects, attributes and behaviors. It provides a clear modular structure. It is easy to maintain and modify the existing code.

(iv) An example of the Object model is Shape, Circle, Rectangle and Triangle are all objects in this model.
(i) Circle has the attribute radius.
(ii) Rectangle has the attributes length and breadth.
(iii) Triangle has the attributes base and height.
(iv) The objects Circle, Rectangle and Triangle inherit from the object Shape.