What is the difference between a table, database and schema?

 The terms table, database, and schema are related concepts in database management systems (DBMS), and each serves a specific role in organizing and managing data. Here's a breakdown of the differences:

1. Table:

   • A table is a collection of related data organized into rows and columns. Each row represents a record, and each column represents a field or attribute of the data.
   • Tables hold the actual data in a relational database.
   • Example: A table called Customers might have columns for CustomerID, Name, Email, and Phone.

2. Database:

   • A database is a collection of tables and other related objects (such as indexes, views, and procedures) that store data.
   • It acts as a container for storing and organizing the data and is managed by a database management system (DBMS).
   • A database typically holds multiple tables and other structures for efficient data access and manipulation.
   • Example: A SalesDB might contain tables such as Customers, Orders, Products, etc.

3. Schema:

   • A schema is a logical container within a database that groups together related database objects such as tables, views, indexes, and procedures.
   • It defines the structure or organization of these objects and provides a way to manage them.
   • In some DBMS, a schema also serves as a way to control access to different parts of a database, as users or roles can be granted permissions to specific schemas.
   • Example: A schema called HR might contain tables like Employees, Departments, and Salaries.

Summary:

• Table: Holds actual data in rows and columns.
• Database: A collection of tables and other related objects.
• Schema: Organizes database objects into logical groups within a database.

The hierarchy can be summarized as: Database → Schema → Table.