AN ASSIGNMENTON

“THE ENTITY RELATIONSHIP DIAGRAM OF HEALTH CARE CENTRE FOR STUDENTS, THE UNIVERSITY OF

BURDWAN”

SUBMITTED TO FACULTY, R.K. GUPTA

CENTRE FOR MANAGEMENT STUDIES, DEPARTMENT OF BUSINESS

ADMINISTRATION THE UNIVERSITY OF BURDWAN.

SUBMITTED BYBIPLAB ANKURI(ROLL-26),PRADEEP KUMAR(ROLL-29)

MBA(GEN.)2009-2011

Acknowledgements

Our heartfelt gratitude to the Faculty, R.K. GUPTA who made us to do this useful assignment. In the initial stage of making this project we have faced many problems but we really contributed, we finally made this assignment. We are thankful to our respected Faculty, R.K. GUPTA without whose guidance this assignment would not been successful.

1. Biplab Ankuri (roll no.-26)

2.Pradeep Kumar (roll no.-29)

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INTRODUCTION

A relationship is an association that exists between two entities. For example, Instructor teaches Class or Student attends Class.

The relationships on an Entity-Relationship Diagram are represented by lines drawn between the entities involved in the association. The name of the relationship is placed either above, below, or beside the line.

ENTITY-RELATIONSHIP MODEL

The entity-relationship diagram is a tool for designing and analyzing databases, and in particular for applying a technique called entity-relationship (ER) modeling to the design process. It has proven to be very successful at rendering the relationships among the data fields, or variables, contained within a given database.

There can be a simple relationship between two entities. For example, Student attends a Class:

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Generally E-R Diagrams require the use of the following symbols

There are three types of relationship cardinality: • one-to-one,• one-to-many,• many-to-many. One-to-One (1:1) A one-to-one relationship between two entities indicates that each occurrence of one entity in the relationship is associated with a single occurrence in the related entity. There is a one-to-one mapping between the two, such that knowing the value of one entity gives you the value of the second. For example, in this relationship an Employee uses a maximum of one Workstation:

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One to Many (1:M), Many to One (M:1)

A one-to-many or a many-to-one relationship between two entities indicates that a single occurrence of one entity is associated with one or more occurrences of the related entity. The example indicates that there is one Project Manager associated with each Project, and that each Project Manager may be associated with more than one Project.

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Many to Many (M:M)

A many-to-many relationship between two entities indicates that either entity participating in the relationship may occur one or several times. The example indicates that there may be more than one Employee associated with each Project, and that each Employee may be associated with more than one Project at a time. That is, projects may share employees.

ENTITY RELATIONSHIP DIAGRAM OF HEALTH CARE CENTRE FOR STUDENTS, THE UNIVERSITY OF BURDWAN

In the health care centre the following conditions are given:

1. The important entities in this situation are the patients and doctors.2. The diagram indicates that a doctor may admit many patients to the

hospital, and just one doctor admits each patient.3. A doctor may treat many patients in the hospital, and a patient may

be treated by a number of different doctors while they are in the hospital.

4. Details of the treatment (date, time and results) are recorded for each treatment.

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The following figure shows a sample entity relationship diagram that represents the relationships between patients admitted to a hospital and the doctors who treat them:

Figure : A sample entity relationship diagram that represents the relationships between patients admitted to a hospital and the doctors who treat them.

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ENTITY SETS ATTRIBUTES KEY ATTRIBUTES

1. DOCTOR Doctor_ID, Doctor_IDSpecialty.

2. PATIENT Patient_Name, Patient_NumberPatient_Number.

Relationships

A relationship in an ERD describes the associations between entities that are of interest to the organisation and users. Relationships are shown in an ERD by a diamond with a description of the relationship written (in lower case letters) in the diamond. Lines connect the diamond to the related entities. In Figure there are two relationships, 'admits' and 'treats'.

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