Schemas and Instances

The data which is stored in the database at a particular moment of time is called an instance of the database. The overall design of a database is called schema. A database schema is the skeleton structure of the database.

1. Database schema
2. Database instance

Database schema

A schema is the blueprint of a database. The names of tables, columns of each table, datatype, functions, and other objects are included in the schema. We use the schema diagram to display the schema of a database.

Note: It is important to note that the schema diagram is not the same thing as the schema.

Note: This schema modification or alteration is known as schema evolution.

Database instance

An instance is the information collected in a database at some specific moment in time, also known as the database state.

A database instance is a set of memory structures that manage database files. A database is a set of physical files on disk created by the CREATE DATABASE statement. The instance manages its associated data and serves the users of the database.