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

Explain nested relations, Explain nested relations? Nested relations ...

Explain nested relations? Nested relations The assumption of INF is a natural one in the bank examples we have considered. However, not all applications are best modelled

What is repository?, Problem 1 Why are the operational system keys not ...

Problem 1 Why are the operational system keys not recommended for forming data warehouse primary keys? Give any two examples 2 Explain the following performance tuning techn

Identify the candidate keys, Consider the following six relation schemes an...

Consider the following six relation schemes and their corresponding sets of functional dependencies. In each case identify a. All the candidate keys b. The highest normal for

Database models, why are older data models are being replaced by new data m...

why are older data models are being replaced by new data models

The extract statement do in extract datasets, What does the extract stateme...

What does the extract statement do in extract datasets? The data is written to virtual memory by extract commands.

Benefits of views-data control, Benefits: It limits data access. ...

Benefits: It limits data access. It makes difficult queries look easy. It permits data independence. It presents dissimilar views of the similar data.

Update anomaly-data redundancy, Update Anomaly : This anomaly is occurred d...

Update Anomaly : This anomaly is occurred due to data redundancy. Redundant information makes updates more complex since, for example, varying the name of the instructor of MCS-014

1) Information about a bank is about customer, 1) Information a...

1) Information about a bank is about customers and their account. Customer has a name, address which consists of house number, area and city, and one or more phone numbers. Ac

Basic concept of data base management system, INTRODUCTION Databases a...

INTRODUCTION Databases and database systems have become an essential part of our daily life. We encounter many activities that involve some interaction with a database almost

Types of indexes, Types Of Indexes One of the words used during the fil...

Types Of Indexes One of the words used during the file organisation is the term index. In this part, let us describe this term in more detail. We find the index of keywords

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