Database Schema and Database Instance
The logical configuration of complete or partial part of the relational database is called the Database Schema. It determines how the data is organized and the way the relations are associated. It puts together all the constraints that are to be applied to the data.
The database Schema is further divided into two types:
- Physical Database Schema: Deals with the storage of data and form of storage. It shows how the data will be reserved in the secondary storage.
- Logical Database Schema: This specifies the logical limitations that are applied to the preserved data.
The collection of data in the entire database at a particular amount of time is called ‘Database Instance’. The instance of a database changes with time.
The Database Schema is designed before the database is even present. It is tough to change once the database is in operation. There is no data present in a Database schema. The DBMS makes sure that all instances are present in a valid state, by occupying the following validations, constraints, and conditions that the database designers have imposed.