State the two-way associations, Database Management System

Assignment Help:

Two-way Associations

Mostly, associations are travel in both directions, although not usually with same frequency. There are three approaches for the implementation.

  • In bi-directional associations, if one direction association is seldom used, then we should implement it as unidirectional association. Searching can perform reverse association. This way, we can reduce storage and update cost.
  • Implementing it as a bi-directional association using the several techniques discussed in previous sections will turn up as shown in Figure. This approach provides faster access but also requires updating of other attributes in case of any change otherwise the link will become inconsistent.

Implementing it as a separate association object, i.e., independent of any class as shown in Figure. The association object can be implemented using two objects: one in forward direction and the other one in the reverse direction. This cause increases efficiency when hashing is used, instead of attribute pointer.

 

584_two way association.png

  Figure:  Implementation of association as an object


Related Discussions:- State the two-way associations

Serialisable schedules, Serialisable Schedules: If the processes of two tra...

Serialisable Schedules: If the processes of two transactions conflict with each other, how to verify that no concurrency related problems have happened? For this, serialisability t

Define partial key and primary key, Define Partial Key and Primary Key ...

Define Partial Key and Primary Key A partial key, also known as discriminator, is the set of attributes which can uniquely identify weak entities that are related to similar o

Forward recovery (redo), Forward Recovery (Redo): In this system the commit...

Forward Recovery (Redo): In this system the committed changes made by a transaction are reapplied to a previous copy of the database.                          In simpler

Memory components of sga, Problem 1. Describe the Oracle Architecture w...

Problem 1. Describe the Oracle Architecture with a neat labeled diagram, Also explain the individual components of the Architecture. 2. Write about the following Oracle 9i o

Control as a state machine engine, Control as a State Machine Engine F...

Control as a State Machine Engine First let us define the state machine: "the state machine is a machine which is an object but not an application object. It is a part of lang

Define the terms entity type and entity set, Define the terms i) Entity typ...

Define the terms i) Entity type ii) Entity set Entity type: An entity type describes a collection of entities that have the similar attributes. Entity set: The set of all en

What are the issues are formed while selecting a database, What are the Iss...

What are the Issues when Selecting a Database Issues when Selecting a Database Storage space requirement: A database requires about triple storage space of the actua

Limitations of file based system, Limitations of File Based System The...

Limitations of File Based System The file-based system has some limitations. The limitations are listed as follows: Isolation and separation of data: When the data is

Triggers and Stored Procedures, 10A.53 Code an Oracle Database trigger to e...

10A.53 Code an Oracle Database trigger to enforce the constraint that an employee can never change his or her department. 10A.54 Code an Oracle Database trigger to allow the delet

Explain the paths in the association network, Explain the paths in the asso...

Explain the paths in the association network We can analyze use of paths in the association network as given below: Calculate each operation Find associations whic

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