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

Physical location of record is determined by which formula, The physical lo...

The physical location of a record is determined by which mathematical formula that transforms a file key into a record location? The physical location of a record is determined

What is the full form of ddl, What is the full form of DDL? DDL is stan...

What is the full form of DDL? DDL is stand for Data Definition Language.

Compare the nested-loop join and block-nested loop join, Compare the Nested...

Compare the Nested-loop join and block-nested loop join Ans: Nested  loop join - It is costly as worst case cost, no. of block accesses needed is n r * b s + b r   where b

Explain the term- collation, What is Collation Collation is a kind of ...

What is Collation Collation is a kind of sort order. There are majorly 3 types of sort orders, namely: i.) Dictionary case insensitive ii.)Dictionary - case sensitive

Guidelines for creation of table, Guidelines for creation of table: ...

Guidelines for creation of table: Table name should begin with an alphabet. In table name, single quotes and blank spaces are not allowed. Reserve words of that DBM

Data manipulation language, Data Manipulation Language Data manipulatio...

Data Manipulation Language Data manipulation language (DML) describes a set of commands that are used to query and change data within existing schema objects. In this case comm

Organic compounds, #question.explain diversity and magnitude of organic com...

#question.explain diversity and magnitude of organic compounds and general properties?

I need web security expert, I need web security expert , website management...

I need web security expert , website management Project Description: i want professional for the below . website management server management database management

In e-r diagram how generalization is represented, In E-R diagram how genera...

In E-R diagram how generalization is represented? in E-R diagram generalization is represented by Triangle shape.

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