Domains, Database Management System

A domain is a set of permissible values that can be given to an attribute. So each attribute in a table has a definite domain. Values to these attributes cannot be assigned outside their domains.

In the example given above if domain of PERSON_ID is a set of integer values from 1 to

1000 than a value outside this range will not be valid. Many other common domains may be age between 1 and 150. The domain can be definite by assigning a type or a format or a range to an attribute. For instance, a domain for a number 501 to 999 can be particular by having a 3-digit number format having a range of values between 501 and 999. Therefore, please note the domains can also be non-contiguous. For instance, the enrolment number of IGNOU has the last digit as the check digit, therefore the nine- digit enrolment numbers are non continuous.

Posted Date: 3/6/2013 5:16:18 AM | Location : United States







Related Discussions:- Domains, Assignment Help, Ask Question on Domains, Get Answer, Expert's Help, Domains Discussions

Write discussion on Domains
Your posts are moderated
Related Questions
Give the forms of triggers? The triggering event can be insert or delete. For updated the trigger can state columns. The referencing old row as clause The referencing

Define Direct file organization? The direct file organization is employed to enhance the performance in accessing the records than sequential file organization. In direct file

What is inheritance? Define it in detail?  Inheritance Inheritance can be at the levels of types, or at the level of tables we first consider inheritance of types, then i

Determine the OBJECTIVES of  object design After passing through this unit, you should be able to: describe and apply concept of generalisation; understand and appl

Wait-die" scheme : The idea is based on non-preventive method. It is based on a simple rule:                                 If Ti requests a database resource that is held by T

1. A company wants a report containing a breakdown of payroll by department. Input, which should be stored in 3 parallel arrays, includes each employee's department number, hourly

online eductional management system ke diagram

What does authentication refer? Authentication refers to the task of verifying the uniqueness of a person.

What is a disjoint less constraint? Ans: It needs that an entity belongs to no much more than one level entity set.  Disjoint less constraint needs that an entity belongs to

Explain how you can define an object model of a system. A list of terms that shall be used by end users to describe state and behaviour of objects in system.   Different use