Domain constraint, Database Management System

Domain Constraint

It shows that each attribute in a relation has to contain an atomic value only from the corresponding domains. The data types associated with commercial RDBMS domains include:

1) Real numbers (double precision floats, float,)

2) Standard numeric data types for integer (such as integer, short- integer,  long integer)

3)  Characters

4)  Fixed length strings and variable length strings.

Therefore, domain constraint shows the condition that we want to put on every instance of the relation. So the values that show in each column must be drawn from the domain associated with that column.

For instance, consider the relation:

STUDENT

 

ROLLNO

 

NAME

 

LOGIN

 

AGE

 

4677

 

Kanu

Golgin_atat@yahoo.com

 

20

 

3677

 

Shikha

 

Noorie_jan@yahoo.com

 

20

 

In the relation above, AGE of the relation STUDENT always relates to the integer domain within a specified range (if any), and not to strings or any other domain. Within a domain non-atomic values should be avoided. This much time cannot be checked by domain constraints. For instance, a database which has area code and phone numbers as two dissimilar fields will take phone numbers as-

 

Area code

 

Phone

 

11

 

29534466

A non-atomic value in this case for a phone can be 1129534466, Though, this value can be accepted by the Phone field.

Posted Date: 3/6/2013 5:26:22 AM | Location : United States







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

Write discussion on Domain constraint
Your posts are moderated
Related Questions
What is persistency? Persistency ensures which data is stored and that after the object is no longer available (program stops running) the data will be available to other users

Consider the following relations: BRANCH( bno, street, area, city, pcode, Tel_no, Fax_no) STAFF( Sno, Fname, Lname, address, position , salary, bno) Express the subsequent qu

#quCreate a database design specification (Enhanced Entity Relationship Diagram (EERD) and Relational Data Model (RDM)) from the given business description. The RDM must be in 3rd

Task Partitioning, Sequencing and Project Planning The tasks required for the service might be broadly partitioned into: 0.      Set up database tables and account file

The JOIN operation is applied on two relations. When we want to choose related tuples from two given relation join is used. The join operation need that both the joined relations m

Need 2 projects completed in 3NF format.

Make SQL statements for the following scenarios. Your response should contain SQL statement, output and any other assumptions you have made to arrive at the answer. For Colorado cu

(a) Explain the three types of potential mistake which could occur if concurrency control is not properly enforced in the database system. Support your answer with appropriate ex

What are the comparison operator in SQL?  Comparison operator in SQL are =, LIKE and BETWEEN

Explain the difference between optimistic locking and pessimistic locking. Optimistic locking supposes no transaction conflict will occur and deals with the consequences if it