Database Management System
Metadata
In database management systems, data files are the files that store the database information, whereas other files, such as index files and data dictionaries, store administrative information known as metadata.
Relationship
Relationships represent a correspondence between the various data elements.
Constraints
Constraints are predicates that define correct database states.
Schema
Schema describes the organization of data and relationships within the database.
The schema defines various views of the database for the use of the computers of the database management system and for the applications security.
A schema separates the physical aspects of data storage from the logical aspects of data representation.
The schema defines various views of the database for the use of the computers of the database management system and for the applications security.
A schema separates the physical aspects of data storage from the logical aspects of data representation.
Types of schema
1.Internal schema
2.Conceptual schema
3. External schema
2.Conceptual schema
3. External schema
Internal schema
The internal schema defines how and where data are organized in physical data storage.
Conceptual schema
The conceptual schema defines the stored data structures in terms of the database model used.
External schema
The external schema defines a view or view of the database for particular users. The database management system provides services for accessing the database while maintaining the required correctness and consistency of the stored data.