Entity integrity constraint - relational constraints, Database Management System

Assignment Help:

It defines that no primary key value can be null. This is as the primary key is used to recognize individual tuple in the relation. So we will not be able to recognize the records uniquely containing null values for the primary key attributes. This constraint is specified on single individual relation.

 Example: Let R be the Table

A#

B

C

Null

B1

C1

A2

B2

C2

Null

B3

C3

A4

B4

C3

A5

B1

C5

Note:

1) '#' shows the Primary key of a relation.

In the relation R above, the primary key has null values in the tuples t1 & t3. NULL value in primary key is not allowed, therefore, relation instance is an invalid instance.


Related Discussions:- Entity integrity constraint - relational constraints

Explain the ansi -sparc schema architecture, (a) Differentiate between info...

(a) Differentiate between information and data . (b) List and briefly explain five potential benefits of the database approach compared to conventional file systems. (c) Diff

Explain the term- inheritance, What is inheritance? Inheritance is an ...

What is inheritance? Inheritance is an object orientation concept that allows reusability of code / design. Basic sense of inheritance is that if one class is predefined than a

Explain categories of failures that occur in oracle database, Explain diffe...

Explain different categories of failures that occur in Oracle database? Categories of Failures - In Oracle database subsequent types of failures can occurred: Statement Failu

Nested relational model, what is Nested relational model? Explain with exam...

what is Nested relational model? Explain with examples.

Write the syntax of creating an index, Write the syntax of creating an INDE...

Write the syntax of creating an INDEX ? Syntax of Creating an Index: CREATE [BITMAP] [UNIQUE] INDEX ON ( [, ] . . .);

What is a primary index, What is a primary index? A primary index is an...

What is a primary index? A primary index is an index whose search key also explains the sequential order of the file.

What are advantages of object-oriented programming paradigm, What is the ma...

What is the major advantage of object-oriented programming paradigm? The ability to modify the explanation of an object without affecting the rest of the system is the main adv

On laod, how to write a in a text and load it on mysql

how to write a in a text and load it on mysql

Enterprise applications integration, The figure below depicts the conceptu...

The figure below depicts the conceptual diagram of a banking system. (a) Describe one example relevant to the system in figure, for each of the 4 types of enterprise appl

What is multiplicity in the associations, What is multiplicity in the assoc...

What is multiplicity in the associations? Give an example to explain multiplicity? Multiplicity in association indicate number of objects participate in any relationship. For

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd