entity relationship diagrams don archer. entity relationship diagram erds – depicts data in terms...

Entity Relationship Diagrams

Don Archer

Entity Relationship DiagramERDs – depicts data in terms of the

entities and relationships described by the data.

Entity DefinitionEntity - is a person, place, thing, or

event of importance to the organization. Anything that can be a noun can be an entity.

Entity Occurrence - One individual instance of a type of entity - the set of data describing an instance of an entity.

Identifying Entities

Identify the nouns in the conversation:

Students may enroll in 12 courses. Classes are scheduled during 6 sessions throughout the year and are identified by sections. Each class may contain 18 students. Students may have several registrations for these classes that are held at 6 locations.

Qualified faculty are assigned to various sections of of the classes. Not all faculty are qualified to teach all courses.


Identify the nouns in the conversation:

STUDENTs may enroll in 12 COURSEs. CLASSes are scheduled during 6 SESSIONs throughout the YEAR and are identified by SECTIONs. Each CLASS may contain 18 STUDENTs. STUDENTs may have several REGISTRATIONs for these CLASSes that are held at 6 LOCATIONs.

QUALIFIED FACULTY are assigned to various SECTIONs of of the CLASSes. Not all FACULTY are qualified to teach all COURSEs.

studentidstudent nameaddresscitystatepostal codefacutlyid (FK)

STUDENT


STUDENT

course nocourse desccredit hours

COURSE

Identifying Relationships

Identify the verbs in the conversation:

STUDENTs may enroll in 12 COURSEs. Classes are scheduled during 6 SESSIONs throughout the YEAR and are identified by SECTIONs. Each class may contain 18 students. Students may have several REGISTRATIONs for these classes that are held at 6 LOCATIONs.

QUALIFIED FACULTY are assigned to various sections of of the classes. Not all FACULTY are qualified to teach all courses.

Identifying Relationships

Identify the verbs in the conversation:

Students may ENROLL in 12 courses. Classes are SCHEDULED during 6 sessions throughout the year and are IDENTIFIED by sections. Each class may CONTAIN 18 students. Students may HAVE several registrations for these classes that are HELD at 6 locations.

Qualified faculty are ASSIGNED to various sections of of the classes. Not all faculty are QUALIFIED to teach all courses.

Identifying Entities & Relations


STUDENT


COURSE

enrolls



STUDENT


COURSE

enrolls

Many-to-many



STUDENT


COURSE

enrolls

course nostudentidgrade

SCHEDULED CLASS

Enrolls inConsists of

studentidstudent nameaddresscitystatepostal codefacutlyid (FK) (IE)

STUDENT


COURSE

consist of/makes up

registers for/registers

yearsessionsection nocourse nofacultyidlocation code

SCHEDULED CLASS

Is This Correct???


STUDENT


COURSE

consist of/makes up



SCHEDULED CLASS

NO!

Many-t

o-man

y

This is a many-to-many relationship


STUDENT


COURSE

consist of/makes up



SCHEDULED CLASS

How do you fix a M:M relation?

yearsessionsection nocourse nostudentid/1studentid (FK) (IE)

CLASS REGISTRATION


STUDENT


COURSE

consist of/makes up


has/is for


SCHEDULED CLASS

Associative Entity

year

YEAR


CLASS REGISTRATION


STUDENT


COURSE

consist of/makes up


has/is for

have/is for


SCHEDULED CLASS

Refinements

year

YEAR

session

SESSION


CLASS REGISTRATION


STUDENT


COURSE

consist of/makes up


has/is for

have/is for

have/is for


SCHEDULED CLASS

Refinements

year

YEAR

session

SESSION

section no

SECTION


CLASS REGISTRATION


STUDENT


COURSE

consist of/makes up


has/is for

have/is for

have/is for

have/is for


SCHEDULED CLASS

Refinements

year

YEAR

session

SESSION

section no

SECTION


CLASS REGISTRATION


STUDENT


COURSE

facutlyidfaculty nameaddresscitystatezipemphasisfacutlyid/1 (FK) (IE)

FACULTY

consist of/makes up


has/is for

is assigned to/has assigned

held at/hosts

have/is for

have/is for

have/is for

location codeloc description

LOCATION


SCHEDULED CLASS

Location

& Faculty

year

YEAR

session

SESSION

section no

SECTION


CLASS REGISTRATION


STUDENT


COURSE


FACULTY

course nofacutlyid (FK)

QUALIFIED FACULTY

consist of/makes up


has/is for

becomes/consitst of

held at/hosts

have/is for

have/is for

have/is for


LOCATION


SCHEDULED CLASS

qualified for/qualified by

year

YEAR

session

SESSION

section no

SECTION


CLASS REGISTRATION


STUDENT


COURSE


FACULTY


QUALIFIED FACULTY

consist of/makes up


has/is for

becomes/consitst of


held at/hosts

have/is for

have/is for

have/is for


LOCATION


SCHEDULED CLASS


year

YEAR

session

SESSION

section no

SECTION


CLASS REGISTRATION


STUDENT


COURSE


FACULTY


QUALIFIED FACULTY

consist of/makes up


has/is for

advised by/advises

becomes/consitst of


held at/hosts

have/is for

have/is for

have/is for


LOCATION


SCHEDULED CLASS


year

YEAR

session

SESSION

section no

SECTION


CLASS REGISTRATION


STUDENT


COURSE


FACULTY


QUALIFIED FACULTY

mentors/is mentored by

consist of/makes up


has/is for

advised by/advises

becomes/consitst of


held at/hosts

have/is for

have/is for

have/is for


LOCATION


SCHEDULED CLASS


Recursive

Business rules Each STUDENT may HAVE one or more CLASS REGISTRATIONS. Each CLASS REGISTRATION must be ASSIGNED to one & only one

STUDENT.

Each CLASS may HAVE one or more CLASS REGISTRATIONs. Each CLASS REGISTRATION must BE FOR one & only one CLASS.

Each COURSE may BE ASSIGNED to one or more SCHEDULED CLASSes.

Each SCHEDULED CLASS must CONSIST on one & only one COURSE.

Business rules Each LOCATION may be ASSIGNED one or more SCHEDULED

CLASSes. Each SCHEDULED CLASS must BE ASSIGNED to one & only one

LOCATION.

Each YEAR may be ASSIGNED one or more SCHEDULED CLASSes. Each SCHEDULED CLASS must BE ASSIGNED to one & only one

YEAR.

Each SECTION may be ASSIGNED one or more SCHEDULED CLASSes.

Each SCHEDULED CLASS must BE ASSIGNED to one & only one SECTION.

Business rules Each FACULTY may ADVISE one or more STUDENTs. Each STUDENT must be ADVISED BY one & only one ADVISOR.

Each QUALIFIED FACULTY must be ASSIGNED to one & only one COURSE.

Each COURSE may be QUALIFIED by one or more QUALIFIED FACULTY.

Each QUALIFIED FACULTY must CONSIST of one & only one FACULTY.

Each FACULTY may be QUALIFIED for one or more QUALIFIED FACULTY positions.

year

YEAR

session

SESSION

section no

SECTION


CLASS REGISTRATION


STUDENT


COURSE


FACULTY


QUALIFIED FACULTY

mentors/is mentored by

consist of/makes up


has/is for

advised by/advises

becomes/consitst of


held at/hosts

have/is for

have/is for

have/is for


LOCATION


SCHEDULED CLASS


Visio

entity relationship diagrams don archer. entity relationship diagram erds – depicts data in terms...

Documents

recursive slide

location faculty slide

entities relations slide

scheduled classes

class registrations

qualified faculty

entity definition entity

various sections