Lec-5: What is Schema | How to define Schema | Database management system in Hindi
What is Schema in a Database?
Introduction to Schema
- The speaker introduces the topic of schema in databases, emphasizing its simplicity yet importance across various contexts and questions related to databases.
Definition of Schema
- A schema is defined as a logical representation of a database, contrasting with the physical storage of data on hard drives or backend servers.
Logical Representation in RDBMS
- In Relational Database Management Systems (RDBMS), data is logically represented through tables or relations, such as entities and their relationships in an Entity-Relationship (ER) model.
Designing a Student Schema
- The speaker illustrates how to design a schema for a student entity, highlighting attributes like roll number, name, and address that form the structure of this entity.
Course Schema Design
- Similarly, when designing a course schema, key attributes include course ID, course name, and duration. This showcases how different entities can be structured logically.
Implementation of Schema
Conceptual vs Physical Representation
- The distinction between logical representation (tables with attributes like roll number and name) versus physical storage on hard disks is discussed.
Three-Schema Architecture
- The three-schema architecture includes a middle layer known as the conceptual schema which represents data logically.
SQL Implementation
- To implement schemas practically, SQL (Structured Query Language), particularly Data Definition Language (DDL), is utilized for commands like create table, alter table, or drop table.
Summary of Key Points
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