Binary relationships, Database Management System

One-to-one relationship:

For every 1:1 relationship type R in the ER diagram including two entities E1 and E2 we take one of entities (say E1) preferably with total participation and add primary key attribute of one more entity E2 as a foreign key attribute in the table of entity (E1). We will also have all the simple attributes of relationship type R in E1 if any.

For instance, the DEPARTMENT relationship has been extended to contain head-Id and attribute of the relationship. Please note we will maintain information in this table of only present head and Date from which s/he is the head.

There is one Head_of 1:1 relationship among FACULTY and DEPARTMENT. We select DEPARTMENT entity having total participation and add primary key attribute ID of FACULTY entity as a foreign key in DEPARTMENT entity named as Head_ID. Now the DEPARTMENT table will be as follows:

DEPARTMENT

D_NO

D_NAME

Head_ID

Date-from

 

 

 

 

 

 

 

 

Posted Date: 3/6/2013 6:26:41 AM | Location : United States







Related Discussions:- Binary relationships, Assignment Help, Ask Question on Binary relationships, Get Answer, Expert's Help, Binary relationships Discussions

Write discussion on Binary relationships
Your posts are moderated
Related Questions
What are the benefits of OOA technology? Using OOA technology can produce many benefits, such as:  i) Reusability of code  ii) Productivity is gained through direct mappi

Control Files : The redo and control files logs support the rest of the architecture. Every database must have at least one control file, although you have more than one to guard

Assume that you are responsible for selecting a new DBMS product for Sohar Hospital

Which data manipulation command combines the records from one or more tables ? JOIN data manipulation command combines the records from one or more tables.

Define the Two Phase Locking Protocol This is a protocol that is used to make sure serializability of transactions. This protocol needs that every transaction issue lock and u

What is abstraction? Abstraction in the object orientation is a idea that provide opportunity to express necessary properties of object without providing much details of the im

Explain the term - Handling Boundary Condition These are some circumstances that to be handled in any system initialization and termination. Describes how system is bro

What's the difference between a primary key and a unique key? Both primary key and unique key enforces uniqueness of the column on which they are explained. But by default prim

Explain the term- Data Flows Data Flows: A data flow connects output of an object or process to input of another process or object. It represents an in-between data value wit

What is Normalization? Database normalization is a data design and organization method applied to data structures based on rules that help building relational databases. In rel