What is an instance in DBMS?

The situation where a data or information is stored in the database at a particular moment of time is called an instance. An instance is also called a current state or database state. The database schema that defines variables in tables which belong to a specific database, the records of these variables at a particular moment are called the instance of the database.

Many instances are constructed to correspond to a specific database schema. Every time we can insert, modify, or delete the value of a data item in a record. One state of data can change into another state.


Consider a table given below which has the Student (Schema) −

Std IDNameCity

In the above table, rows are called instances.

Finally, we can say that the content of database at a point of time is called instance or database state.

There are three types of states present in database −

  • Empty state: When ever a new database is defined.

  • Initial state: first time data is loaded in database.

  • Current state: the present operation is applied to database.

The instance of a student relation is −

For example − students ( studentID: string, student_name: string, Login:string, age: integer);

Instance −