The company is organized into departments and each department has a unique name and main office. The department has a particular employee who manages the

The company is organized into departments and each department has a unique name and main office. The department has a particular employee who manages the department. We should keep track of the date when that person started managing the department. We should also keep track of all of the offices that are assigned to the department. Each office has a building name, room number and a telephone.

Nouns = possible data items

(only the first occurrence is highlighted)


A department controls a number of projects, each of which has a unique number within the company. Each project also has a description, employee who serves as its director, and budget. The company also wants to keep track of all employees who are assigned to each project.

We want to keep track of each employee’s name. social security number, address, salary, sex, birthdate, and starting date of employment with the company. Each employee belongs to a department but may work on projects that are controlled by departments other than the one to which he or she is assigned. We also want to keep track of the number of hours each employee has worked on each project

Data Items Found(= Entities or Attributes)

department

(department) name

(department) main office

employee

(department) manager

date started managing department

offices

(office) building

(office) room

(office) telephone

project

(project) number

(project) description

(project) budget

(project) director

(employee) name

social security number

address

salary

sex

birthdate

starting date (of employment)

number of hours worked

Verb phrases = possible relationships


A department controls a number of projects, each of which has a unique number within the company. Each project also has a description, employee who serves as its director, and budget. The company also wants to keep track of all employees who are assigned to each project.

We want to keep track of each employee’s name, social security number, address, salary, sex, birthdate, and starting date of employment with the company. Each employee belongs to a department but may work on projects that are controlled by departments other than the one to which he or she is assigned. We also want to keep track of the number of hours each employee has worked on each project

department has a name.

department has a main office.

employee manages a department

offices are assigned to a department

office has a building name

office has a room number

office has a telephone

department controls a project

project has a unique number

project has a description

project has an employee

employee who serves as director

project has a budget

employee is assigned to a project.

employee has a nameemployee has a social security numberemployee has a addressemployee has a salaryemployee has a sexemployee has a birthdateemployee has a starting date of employmentemployee belongs to a departmentemployee works on projects

projects are controlled by departments

employee worked on a project

Modeling Principles:

• Use common form for all synonyms• nouns suggest either entities or attributes• possessive or“has a” often designates an attribute• other verb phrases often designate relationships

Draw Entities

EMPLOYEE

EMPLOYEESSN

EMPLOYEESSN

Name

EMPLOYEE

Address

SSN

Name

EMPLOYEE

Address Salary

SSN

Name

EMPLOYEE

Address SalarySex

SSN

Name

EMPLOYEE

Address SalarySex

BirthdateSSN

Name

EMPLOYEE

Address SalarySex

BirthdateSSN

StartdateName

EMPLOYEE

Address SalarySex

BirthdateSSN

StartdateName

DEPARTMENT

EMPLOYEE

Address SalarySex

BirthdateSSN

StartdateName

DEPARTMENTName

EMPLOYEE

Address SalarySex

BirthdateSSN

StartdateName

DEPARTMENTName

Main Office

EMPLOYEE

Address SalarySex

BirthdateSSN

StartdateName

DEPARTMENTName

Main Office

Building

EMPLOYEE

Address SalarySex

BirthdateSSN

StartdateName

DEPARTMENTName

Main Office

Building Room

EMPLOYEE

Address SalarySex

BirthdateSSN

StartdateName

DEPARTMENTName

Main Office

Building Room Phone

EMPLOYEE

Address SalarySex

BirthdateSSN

StartdateName

DEPARTMENTName

Main Office

Building Room Phone

Office

Building Room Phone

EMPLOYEE

Address SalarySex

BirthdateSSN

StartdateName

DEPARTMENTName

Main Office

Building Room Phone

Office

Building Room Phone

PROJECT

PROJECTNumber

PROJECT

Description

Number

PROJECT

Description

BudgetNumber

Draw Relationships

(attributes are omitted for clarity)

BelongsTo

EMPLOYEE DEPARTMENT

BelongsTo

EMPLOYEE DEPARTMENTManages

BelongsTo

EMPLOYEE DEPARTMENTManages

StartDate

BelongsTo

EMPLOYEE DEPARTMENT

PROJECT

Manages

StartDate Controls

BelongsTo

EMPLOYEE DEPARTMENT

PROJECT

Manages

StartDate

Directs

Controls

BelongsTo

EMPLOYEE DEPARTMENT

PROJECT

Manages

StartDate

WorksOn

Controls

Directs

BelongsTo

EMPLOYEE DEPARTMENT

PROJECT

Manages

StartDate

WorksOn

Controls

Hours Directs

Specify Attributes and Domains

Attribute Domain Data Type Constraints

Employee.Name EmpNameDom String Max length 40

SSN SSNDom String ###-##-####

Address AddressDom String Max length 60

Salary Integer 0

Sex {M,F}

Birthdate Date

Employee.Startdate Date

Department.Name DeptNameDom String Max length 15

MainOffice OfficeDom (Building, Room, Phone)

Office Set of OfficeDom

Building BuildingDom String Max length 10

Room RoomDom String Max length 3

Attribute Domain Data Type Constraints

Phone PhoneDom String ###-###-####

Number ProjectNumDom Integer 0

Description ProjDescDom String Max length 40

Budget Integer

Manager.StartDate Date

WorksOn.Hours Integer 0

Documents

The company is organized into departments and each department has a unique name and main office. The department has a particular employee who manages the