DBMS DBMS Architecture

DBMS Architecture

DBMS Architecture contains Schemas, Sub-schemas and Instances

Schemas:

The overall logical design of the database.

Sub-Schemas:

A sub schema is a subset of the schema and inherits the same property that a schema has. The plan (or scheme) for a view is often called sub-schemas.

Instances:

The collection of information stored in the database at a particular moment.

The difference between Schema and Instance are given in below table.

  Schema Instance
Definition The overall logical design of the database. The collection of information stored in the database at a particular moment.
Includes Table names,column names, datatypes, and size of columns, various constraint at logical level. Actual data or information stored in tables in form of different records.
Change changes infrequently. changes frequently.
Cause of change insertion of tables or columns and change in datatype,size or constraints on any column. insert,delete or update operation on data stored in database.
Analogy variable declaration value of the variable


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