DBMS

   Relational Database A relational database is a type of database that stores data in the form of tables. These tables are also called relations. Each table consists of rows and columns, where rows represent records and columns represent attributes. The relational database model was introduced by Edgar F. Codd in 1970. It is one of the most widely used database models in the world because of its simplicity, flexibility, and strong data integrity features. In a relational database, data is organized into structured tables, and relationships between tables are established using keys such as primary keys and foreign keys. This structure helps maintain consistency and avoids duplication of data. Each table focuses on a specific entity, such as students, employees, or products, and relationships connect related information across multiple tables. Popular relational database management systems (RDBMS) include: MySQL Oracle Database Microsoft SQL Server PostgreSQL ...

  Relational Algebra in DBMS Relational Algebra is a procedural query language used in a Database Management System (DBMS) to perform operations on relational databases. It forms the theoretical foundation of relational database systems. Relational Algebra operates on tables (relations) and produces new tables as results. It provides a set of operations that help users retrieve and manipulate data stored in relational databases. Modern database systems such as MySQL , Oracle Database , Microsoft SQL Server , and PostgreSQL are based on relational algebra concepts. Relational Algebra is called procedural because it specifies what operation to perform and how to perform it to get the desired result. Each operation takes one or more relations as input and produces a new relation as output. This property is known as closure property, meaning the result of an operation is always another relation. 🔹 Basic Operations in Relational Algebra The basic operations are fundamental operat...

  Keys in DBMS  In a Database Management System (DBMS), a key is an attribute or a set of attributes used to uniquely identify a record in a table. Keys play a very important role in maintaining data accuracy, integrity, and relationships between tables. Without keys, it would be difficult to distinguish between records, especially when tables contain large amounts of data. Keys help prevent duplicate records, enforce rules, and establish connections between related tables. For example, in a student table, many students may have the same name, but each student will have a unique roll number or ID. That unique value is called a key. Keys ensure that every record can be uniquely identified and accessed efficiently. 🔹 Types of Keys in DBMS 1️⃣ Primary Key A primary key is a column or a combination of columns that uniquely identifies each record in a table. It cannot contain duplicate values and cannot be NULL. Every table should have at least one primary key. The primary k...

   Database Architecture : Database architecture refers to the overall design and structure of a database system that defines how data is stored, accessed, and managed. It explains how users, applications, and the database interact with each other. A good database architecture ensures data security, consistency, performance, and scalability. Modern database systems such as MySQL , Oracle Database , Microsoft SQL Server , and PostgreSQL use structured architectural models to manage large amounts of data efficiently.  Key Points of Database Architecture Defines how data is organized and stored Controls how users access the database Ensures data security and integrity Improves system performance Supports scalability for large applications Provides data independence Helps in easy maintenance and management

    What is SQL? SQL (Structured Query Language) is a standard language used to manage and manipulate relational databases. It is used in database systems like: MySQL PostgreSQL Oracle Database Microsoft SQL Server SQL allows users to create databases, insert data, update records, retrieve information, and control access. 🔹 Types of SQL Commands SQL commands are divided into five main categories: DDL – Data Definition Language DML – Data Manipulation Language DQL – Data Query Language DCL – Data Control Language TCL – Transaction Control Language 🔹 1. DDL (Data Definition Language) DDL commands are used to define and manage the structure of database objects like tables. ✅ CREATE Used to create new databases, tables, views, or other database objects. ✅ DROP Used to permanently delete database objects such as tables or databases. ✅ ALTER Used to modify the structure of an existing table (add, delete, or modify columns). ✅ TRUNCATE...

Velammal College of Engineering and Technology, Madurai – 625 009 Department of Computer Science and Engineering Syllabus Course Code-Title 21CS206 – DATABASE MANAGEMENT SYSTEMS Course Component Professional Core Contact Hours Lecture Tutorial Practical Total Hours Credit 3 0 0 45 3 Course Assessment methods  Continuous Semester-end assessment Internal Assessment Tests and Assignments End semester exam, Student Course exit survey Prerequisite Courses Working Knowledge on Computers Data structures Course Objective To explain the fundamentals of data models and to represent a database system. To describe the internal storage structures using different file and indexing techniques which will help in physical DB design. To illustrate the fundamental concepts of transaction processing- concurrency control techniques and recovery procedures. To demonstrate Storage and Query processing Techniques. To develop a solutions to the real time problems using NoSQL. TOPICS TO BE COVERED UNIT I - ...