Key constraint - relational constraints, Database Management System

Assignment Help:

This constraint shows that the key attribute value in each tuple must be unique, i.e., no two tuples have the similar value for the key attribute. This is because the value of the primary key is used to recognize the tuples in the relation.

 

Example: If A is the key attribute in the following relation R than A1, A2 and A3 must be unique.

 

A

 

B

 

A1

 

B1

 

A3

 

B2

 

A2

 

B2

 

Example: In relation PERSON, PERSON_ID is primary key so PERSON_ID cannot be given as the similar for two persons.

Integrity Constraint

There are two kinds of integrity constraints:

  • Entity Integrity Constraint
  • Referential Integrity Constraint

Related Discussions:- Key constraint - relational constraints

Determine advantages of merging an association into a class, What are the a...

What are the advantages and disadvantages of merging an association into a class?  Advantages: i)  Less number of tables ii) Faster performance due to the fewer tables

Data, Explain three main attributes of data.

Explain three main attributes of data.

Explain sequential file organization, Question 1 What do you mean by datab...

Question 1 What do you mean by database management system? Question 2 Write a note on Object-Oriented Model Question 3 Explain Sequential File Organization Question

Create a table for database transformation , Step 1 . Using Oracle, create ...

Step 1 . Using Oracle, create the tables identified in the preferred solution for Assignment 2. Technicians (ZipCode, TechnicianID, FirstName, LastName, Street, City, State, Home

Define network dbms, Define Network DBMS The NDBMS is built primarily o...

Define Network DBMS The NDBMS is built primarily on a one-to-many relationship, but where a parent-child representation between the data items cannot be ensured. This may occur

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

what is Nested relational model? Explain with examples.

The data of a view is not physically stored, The data of a view is not phys...

The data of a view is not physically stored, but derived from one or more tables. True the data of a view is not physically stored

Define and differentiate among ordered indexing and hashing, Define and dif...

Define and differentiate between ordered indexing and hashing. Ans: Ordered indexing: To gain fast random access to records in a file, we can make of an index structure. Every

RDBMS, Benefits and limitations

Benefits and limitations

Describe the types of attributes, Describe the types of attributes? Ty...

Describe the types of attributes? Types of attributes: An attribute's category determines the type of values that are permitted in the attribute. For instance, the value vers

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