What is Database Schema

• In the context of databases, a schema refers to the logical organization or structure that defines how data is stored, arranged, and accessed within the database. It serves as a blueprint or plan that outlines the database's design, including tables, fields, relationships, constraints, and other elements.

A database schema defines the following components:

• Tables: A table is a collection of related data organized in rows and columns. Each table represents a specific entity or concept, and the rows in the table represent individual instances or records of that entity. For example, in a database for a company, there might be tables for employees, departments, and projects.

• Columns (Attributes): Columns, also known as attributes or fields, define the data elements within a table. Each column represents a specific property or characteristic of the entity represented by the table. For example, in an "Employees" table, columns might include "EmployeeID," "FirstName," "LastName," "Email," and "DepartmentID."

• Relationships: The schema defines the relationships between different tables in the database. These relationships establish how the data in one table is related to the data in another table. Common relationship types include one-to-one, one-to-many, and many-to-many.

• Primary Keys: A primary key is a column or set of columns that uniquely identifies each row in a table. It ensures that each record can be uniquely identified and is used as a reference point in defining relationships between tables.

• Constraints: Constraints are rules that enforce data integrity and validity within the database. Common constraints include unique constraints, which ensure that a specific column or combination of columns contains unique values, and foreign key constraints, which maintain referential integrity between related tables.

• Views: A view is a virtual table created from one or more tables or views. It represents a subset of the data in the database and provides a simplified or customized view of the underlying data.

• Database schemas play a crucial role in maintaining the structure and integrity of the data stored in a database. They provide a standardized way to organize and access data, making it easier for developers, administrators, and users to work with the database effectively.