(i) SELECT Operation (symbol : σ): The SELECT operation is used for selecting a subset with tuples according to a given condition.
(ii) PROJECT Operation (symbol: II): The projection eliminates all attributes of the input relation but those mentioned in the projection list. The projection method defines a relation that contains a vertical subset of Relation.

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 F Codd Rules.

SQL server, Oracle, MySQL, MariaDB, SQLite.

DBMS Supports Transactions : It allows us to better handle and manage data integrity in real world applications where multi-threading is extensively used.

(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.

(i) Database is a repository collection of related data organized in a way that data can be easily accessed, managed and updated.
(ii) Database can be a soft ware or hardware based, with one sole purpose of storing data.

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.

Data Consistency means that data values are the same at all instances of a database.

(i) SQL server
(ii) Oracle
(iii) MySql
(iv) Maria DB
(v) SQLite.

(i) Foxpro
(ii) dbase

(i) Relation
(ii) Tuple
(iii) Attribute

(i) Table is the entire collection of related data in one table, referred to as a File or Table where the data is organized as row and column.
(ii) Each row in a table represents a record, which is a set of data for each database entry.
(iii) Each table column represents a Field, which groups each piece or item of data among the records into specific categories or types of data. Eg. StuNo., StuName, StuAge, StuClass, StuSec.,
A Table is known as a RELATIQN
A Row is known as a TUPLE
A column is known as an ATTRIBUTE

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

Advantages of DBMS:
(i) Segregation of application program
(ii) Minimal data duplication or Data Redundancy
(iii) Easy retrieval of data using the Query Language
(iv) Reduced development time and maintenance

(i) A DBMS is a soft ware that allows us to create, define and manipulate database, allowing users to store, process and analyze data easily.
(ii) DBMS provides us with an interface or a tool, to perform various operations to create a database, storing of data and for updating data, etc.
(iii) DBMS also provides protection and security to the databases. It also maintains data consistency in case of multiple users.

(i) A database is an organized collection of data, generally stored and accessed electronically from a computer system.
(ii) The term "database" is also used to refer to any of the DBMS, the database system or an application associated with the database
(iii) Because of the close relationship between them, the term "database" is often used casually to refer to both a database and the DBMS used to manipulate it.

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

Characteristics of Database Management System

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:

σ course = "Big Data" (STUDENT) 

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:

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

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:

Result:

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:

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:

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.

Types of relationships:
(i) One-to-One Relationship
(ii) One-to-Many Relationship
(iii) Many-to-One Relationship
(iv) Many-to-Many Relationship
(i) One-to-One Relationship: 
In One-to-One Relationship, one entity is related with : only one other entity. One row in a table is linked with only one row in another table and vice versa.
For example: A student can have only one exam number

(ii) One-to-Many Relationship.
In One-to- Many relationship, one entity is related to many other entities. One row in a table A is linked to many rows in a table B, but one row in a table B is linked to only one row in table A.
For example: One Department has many staff members.

(iii) Many-to-One Relationship:
In Manyto- One Relationship, many entities can be related with only one in the other entity.
For example:
A number of staff members working in one Department.
Multiple rows in staff members table is related with only one row in Department table.

(iv) Many-to-Many Relationship:
A manyto- many relationship occurs when multiple records in a table are associated with multiple records in another table.
(i) Example 1: 
Customers and Product
Customers can purchase various products and Products can be purchased by many customers
(ii) Example 2:
Students and Courses
A student can register for many Courses and a Course may include many students
(iii) Example 3:
Books and Student.
Many Books in a Library are issued to many students.