What is inheritance, Database Management System

Assignment Help:

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 inheritance at the level of labels.

Type inheritance

Assume that we have the following type definition for people

create type person

(name varchar(20)

address varchar(20))

Table inheritance

Create table people of person

The consistency requirements for sub tables are

1. Each tuple of the sub table can correspond to at most single tuple in each of its immediate sub tables.

2. SQL:1999 has an additional constraint that all the tuples corresponding to each other must be derived from single tuple .

 


Related Discussions:- What is inheritance

What is a view, What is a view?  Make a view of EMP table named DEPT 20, to...

What is a view?  Make a view of EMP table named DEPT 20, to display the employees in department 20 and their annual salary.  Ans:  View is a virtual table that does not consist

What are advantages of object models, What are advantages of object models?...

What are advantages of object models? Object models are efficient for communicating with the application experts and reaching a consensus about the significant aspects of the p

What does the cardinality ratio specify, What does the cardinality ratio sp...

What does the cardinality ratio specify? Mapping cardinalities or cardinality ratios state the number of entities to which another entity can be associated. Mapping cardinaliti

Computer, what is object-identity

what is object-identity

Explain the term - adjustment of inheritance, Explain the term - Adjustment...

Explain the term - Adjustment of inheritance The inheritance can be enlarged as object design progresses by changing class structure. The designer should do: i) Adjust or r

What is dml, What is DML (Data Manipulation Language)? This language th...

What is DML (Data Manipulation Language)? This language that enable user to access or manipulate data as organised by appropriate data model. Procedural DML or Low level: DM

What are the physical characteristics of magnetic disks, What are the physi...

What are the physical characteristics of magnetic disks?   Ans: A magnetic disk is a circular plate or platter of plastic or metal that is coated with magnetizable material lik

Display how records can be deleted and updated in qbe, With the help of an ...

With the help of an example display how records can be deleted and updated in QBE. (i) Increase Pay_Rate of employees along with the skill of ‘cook' by 10%. (ii) Delete employee

Which is another name for weak entity, Which is another name for weak entit...

Which is another name for weak entity? Child is another name of weak entity.

Which method of access uses key transformation, Which method of access uses...

Which method of access uses key transformation? A Hash method of access uses key transformation.

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