Relation and relational schema, Database Management System

A relation has:

  • Relational Schema
  • Relation instance

Relational Schema:

A relational schema shows the relation's name, its attributes and the domain of every attribute. If R is the name of a relation and A1, A2...An is a list of attributes showing R then R (A1, A2...An) is known as a relational schema. Every attribute in this relational schema takes a value from some explicit domain called Domain (Ai).

For instance, the relational schema for relation PERSON as in Figure will be: PERSON (PERSON_ID:integer, NAME: string, AGE:integer, ADDRESS:string)

Total number of attributes in a relation indicates the degree of a relation. Hence the

PERSON relation includes four attributes, so this relation is of degree 4

Posted Date: 3/6/2013 5:16:52 AM | Location : United States

Related Discussions:- Relation and relational schema, Assignment Help, Ask Question on Relation and relational schema, Get Answer, Expert's Help, Relation and relational schema Discussions

Write discussion on Relation and relational schema
Your posts are moderated
Related Questions
Describe the GRANT function and explain, how it associates to security. What kind of privileges may be granted? How are they revoked? Ans: Since more than one user can aacce

Economics: It is now usually accepted that it costs less to make a system of smaller computers with the equivalent power of a one large computer. It is more cost-effective to get s

What types of adjustments are required to increase chances of inheritance. a)   Some attributes can be added or ignored in  the base class operation  b) Some changes can be

Explain Authorization and Integrity Manager ? Authorization and Integrity Manager: Tests for the satisfaction of integrity constraints and checks the authority of users to acce

Aggregation Aggregation is stronger form of association. It represents the "has-a" or "part-of" relationship. An aggregation association depicts a complex object which is comp

Update Operations and Dealing with Constraint Violations There are three basic operations to be executes on relations: Insertion Deletion Update The INSER

differences between a classified catalog and a dictionary catalog

Increased overheads on update : On the drawbacks side, it will need the system to ensure that all replicas of a relation are consistent. This shows that all the replicas of the rel

What are the advantages of relational data model? Normal 0 false false false EN-IN X-NONE X-NONE MicrosoftInternetExplorer

Question: The following relational database schema corresponds to a part of a database used by the Registry Department of a university. DEPARTMENT (d#, d-name, head-of-dept)