1. ORGANIZING DATA AND INFORMATION-II (Business & Data modeling)
Chandra S. Amaravadi

2. IN THIS PRESENTATION.. Quick Review entity, entity class, attribute
database file, record, attribute, attribute value
schema, primary key
dbms activities
Database planning
Database requirements (modeling)

3. DATABASE PLANNING

4. PLANNING OBJECTIVES
The objective of planning is to get an overall understanding
of organization’s data and resource requirements:
preliminary understanding of data requirements
resource requirements
assess size of database
Scope, timeline
What is a systematic way of obtaining an overview of data?

5. PLANNING METHOD Planning method is called Business systems planning
Understand background of the organization
Study functions and processes
Preliminary understanding of data-function relationships. What function creates what data?
Develop EA (Planning) matrices & Enterprise Data Model
Use for planning/scope/schedule/resource requirements

6. ENTITY-RELATIONSHIP (ER)
DATABASE ANALYSIS
USING
ENTITY-RELATIONSHIP (ER)
APPROACH

7. DATABASE ANALYSIS Next step after planning
Develop an integrated model of data reqmts.
ER Developed in 1976 by Chen to model data relationships
Main concepts are :
entity classes,
attributes and
Relationships
How are entity classes and attributes identified?

8. MODELLING ENTITY CLASSES
Entity Class – Collection of related entities.
FLIGHTS
AVIS
PRODUCTION
ord#
BOOKING
PROPERTY
Common nouns (singular or plural doesn’t matter)
Customers, Products, Students etc.
Cannot be attributes or proper nouns (e.g. ‘TESLA’)
Cannot be database/IT concepts

9. MODELLING ATTRIBUTES
Attribute – Property or characteristic of an entity class
Generally on top of eclass
or below eclass
Use ovals
Pkey is leftmost attribute &
underlined
attr. not duplicated except for
pkey
from to
flt#
FLIGHTS
Pkey – An attribute whose values are unique within a table

10. FOR DISCUSSION For a residential real estate organization, identify
which of the following are:
Eclasses
attributes
relevant and not relevant?
listing#
sale id
advertisement
owner
employee bonuses
refrigerator s.no
bedrooms
newsletter
square footage
property
taxes on property
farm equipment
building permit
construction season

11. MULTI-VALUED ATTRIBUTES..
Sometimes attributes have more than one set of values
per entity instance. to
from
fare
flt#
FLIGHTS

12. MODELLING RELATIONSHIPS
Relationships: logical and meaningful connections
between two or more entity classes. to
pname
addr
from
flt#
FLIGHTS
reserved
PASSENGERS
Use diamonds, label
L-R, T-B order
Indicate cardinality (1:1, 1:M, M:N)

13. AVOID FLOWCHARTING places are for CUSTOMER ORDERS PRODUCTS places
SHOULD NOT BE A PROCESS FLOW
places
orders
CUSTOMER
ORDERS
PRODUCTS

14. CARDINALITY CARDINALITY -- Number of entities that participate in a
relationship. Can be 1:1, 1:M or M:N
Between two entity classes A and B, these are defined as follows:
1:1 -- Each instance of A is associated with one instance of B
and vice versa.
1:M -- Each instance of A is associated with many instances of B.
Each instance of B is associated with one instance of A.
M:N -- Each instance of A is associated with many instances of B
Max cardinality rule: in 3-way & above, use max cardinality

15. THREE WAY RELATIONSHIPS
Agencies book flights for passengers
AGENCIES
book
FLIGHTS
PASSENGERS
in 3-way & above, use max cardinality

16. RELATIONSHIP ATTRIBUTES
Attributes that belong with a relationship rather than with
an eclass. E.g. agencies book flights for passengers on a certain date
date
FLIGHTS
booked
PASSENGERS
AGENCIES
Include airlines

17. CLASS/SUBCLASS RELATIONSHIPS..
Entity classes
can be grouped
into
parent/child
or superclass/class or class/subclass
relationships
based on
common
characteristics.
PASSENGERS
Class/Superclass
Is-a
BUSINESS
LEISURE
Sub
-classes

18. DRAWING THE ER CHART List eclasses and attributes, use format below
Identify relationships among eclasses
Decide which relationships to show
Verbalize relationships
Use rectangles for eclasses, diamonds
for relationships and ovals for attributes
Underline pkey
Use only horizontal and vertical connectors
Prod: prod#, descr., price, qty
subclasses: tables, chairs…
Cust: cust#, name, dt. Joined
subclasses: new, returning

19. SOME GUIDELINES.. Label eclasses, attributes and relationships
Pkey should be left most attribute and underlined
Depict the cardinalities
Use max cardinality for 3-way and above
Do not repeat attributes; do not show cross-reference keys
If developing for an organization, do not include name of organization or organization e.g. IRS, DMV

20. ER CHECK LIST all entity classes depicted? no unnecessary duplication?
all attributes included/labelled?
multivalued attr. shown (if any)?
derived/system attr. omitted?
Pkeys marked? fkeys omitted?
Relationships correct/labelled?
Cardinalities shown?
Cycles avoided?

21. DISCUSSION Draw Data Models (ER models) corresponding to the following
Situations:
A property can be business or residential property. It can have one
or more owners. An owner can own more than one property.
A professional publication can have single author or multiple authors.
The author could be affiliated with a company or with a university.
A publication has the author names, journal title, volume, year, and page#.
A person(s) may bid for one or more items at an auction. The bid
price is specified at the time of bidding. This has to be more than the start price. There are multiple auctions at any given time. Persons could bid for multiple items in multiple auctions.

22. DISCUSSION..
Draw Data Models (ER models) corresponding to the following
situations:
A person makes a reservations for flights. A reservation can consist of one or more flights. A flight is operated by one or more airlines. A flight has a flt#, origin, destination, dep. time, arr. time and # of passengers. Airlines can be domestic or international. They have a code, a full name, terminal and contact information.
Legal situation: A case can be a civil or criminal case and is tried in a particular
court (such as the 9th judicial circuit court). The party pressing the lawsuit is
called the plaintiff and the accused is called the defendant. The defendant can have an attorney or a public defender if they cannot afford one. The attorney for the plaintiff is called the prosecuting attorney. Attorneys present evidence for or against the case (no need to distinguish between these two) and could use
objects or witnesses. A judge decides admissible evidence and presides over the case. A jury evaluates the case and passes a verdict of “guilty” or “not guilty”

23. DISCUSSION.. Develop a data model for an order fulfillment center with
the following conditions (make relevant assumptions)
Customer places one or more orders
Each order is for one or more of the company’s products
An order can have multiple invoices
Orders are entered by sales representatives
Orders are shipped by carriers
Each shipment has a bill of lading.
Products and shipments are stored in warehouses
A shipment contains more than one order
A carrier can deliver multiple shipments
A shipment is delivered by one carrier only

24. Multivalued attributes
Entity classes
Relationships
Attributes
Multivalued attributes
Is-a
Class/ subclass
1 : 1
1 : M
M : N
Relationship attributes

25. SUMMARY OF CONCEPTS Term Definition Enterprise Data Model
The data model created during the planning process.
Enterprise Analysis Matrix (EA matrix)
This is also called the planning matrix. It shows relationships between processes or activities and entity classes (information classes)
Entity
Individual example of person, place or thing.
Entity Class
Collection of related entities.
Attributes
Properties of entity classes about which we
would like to collect information.
Relationship
Logical and meaningful connection between
two or more entity classes.
Class/subclass
Grouping of entity classes based on common characteristics.
Cardinality
Number of entities participating in a
relationship.
Max cardinality
In 3 way relationships and above use max cardinality.

26. ER RULES Use only horizontal and vertical lines.
Entities are not shown e.g. Avis, Cisco, Western Illinois University.
If the model is developed for a single organization, it is not shown.
Attributes should be placed with the eclasses to which they belong
‘Patient id’ belongs to patient. ‘Lab test’ does not belong to patient class
or physician class but to ‘treatment’ class
Attributes cannot be duplicated except for pkey
Attributes should be connected only to eclasses (or relationships)
Attributes cannot be connected to other attributes
If pkey is not given, it can be assumed
Eclass cannot be connected directly to another eclass
Eclasses can be connected with other eclasses only with
relationship symbol or class/subclass symbol
Relationships must be labelled.
“is-a” is always the label for class-subclass relationships
Cardinality is not shown in class-subclass relationships
Where degree is > 2 use max cardinalities
Cycles and derived attributes must be avoided