Binary relationships, Database Management System

Assignment Help:

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

 

 

 

 

 

 

 

 


Related Discussions:- Binary relationships

What is bankers algorithm, What is banker's algorithm?  Banker's algori...

What is banker's algorithm?  Banker's algorithm is a deadlock avoidance algorithm that is applicable to a resource-allocation system with multiple instances of each resource ty

Describe the objective of structural diagrams, Describe the objective of St...

Describe the objective of Structural Diagrams The main objective of structural diagram is to visualize, construct, specify and document static aspects of a system. Their eleme

Transactions t1 and t2 are in a deadlock, Evaluate: a.When transactions...

Evaluate: a.When transactions T1 and T2 are in a deadlock, one of the transactions will eventually implement to completion and let the other one continue implementation. b.

When it is better to use files than a dbms, When It is better to use files ...

When It is better to use files than a DBMS? It is better to use files than a DBMS when Multiple users wish to access the data.

DSS, WHAT IS DSS? WRITE ITS REQUIREMENTS.

WHAT IS DSS? WRITE ITS REQUIREMENTS.

Implementation of association as an object, Implementation of association a...

Implementation of association as an object Implement as a separate association object, independent of either class, as in Figure. An association object is a group of pairs

E - r schema with weak entity, Consider the E/R schema with weak entity set...

Consider the E/R schema with weak entity sets shown below. Come up with the SQL CREATE TABLE statements (with appropriate primary key, unique and foreign key constraints). Include

What is the archtetype pattern, What is the archtetype/instance pattern? ...

What is the archtetype/instance pattern? The archetype/instance pattern happens when one entity tracks occurrences of another entity. A common example is the relationship among

Describe sequential file organization, Describe sequential file organizatio...

Describe sequential file organization.  Explain the rules for (i)  Inserting a new record. (ii)  Deleting an existing record.          Ans:A sequential f

Write the queries in relational algebra, Problem: You are given the fol...

Problem: You are given the following schema 1. Flights(flno, from, to, distance) 2. Aircraft(aid, flno, aname, cruisingRange) 3. Certified(eid, aid) 4. Employees(eid, ena

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