DBMS Architecture contains Schemas, Sub-schemas and Instances
The overall logical design of the database.
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.
The collection of information stored in the database at a particular moment.
| 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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