Three level architecture

DBTG developed proposal for DB

• 1970

• 1975

• 1971

Entity attributes relationship are defined at

• External level

• Conceptual level

• Internal level

Extension is performed after——— of database has been finalized

• Intension

• Structure

• Storage of DB

Sub schemas is another name of

• Conceptual schemas

• External schemas

• Internal schemas

Virtual data is observed at

• External level

• Conceptual level

• Internal level

Internal level is responsible to store data on

• Storage media

• Files orgnization

• Data structure

• All

Conceptual level contain

• Definition of data

• Structure of data

• Type of data

• All

Three level are depicted by three models known

• External schemas

• Internal schemas

• Three level schemas

• Conceptual schemas

Database schemas is also called

• Extension of database

• Intension of database

• Three level schemas

Space utilisation is performed by

• Encoding scheme

• Data compression

• Indexing