$*$Please do a diagram model in ERDplus or similarily$*1.$ Create an E$-$R model for a business organization described here $(50$ points$)$:

ConstructCO is a $$large$$ construction company that executes large$-$scale infrastructure projects.

This company only takes jobs that are greater than $5$ million in order value. Typical projects

implemented by this company are construction of electric power stations, refineries, large oil drilling

sites, airports etc. A typical project involves design, construction, testing, and commissioning$1$

activities. ConstructCo relies on vendors. Typically a project site looks like a small town with

hundreds of agencies and thousands of workers stationed at the location for several months.

ConstructCO is capable of executing multiple projects at the same time. Some of the salient

operational information is described below:

$($a$)$ CoolAir$2$

is a small Air$-$conditioner sales and service company serving the local home owners

in RGV by offering a variety of services including repairing air conditioners and installing new

ones if the old ones are broken.

$($b$)$ CoolAir is owned by John Watts. Until now, John has used simple IT tools such as MS Excel

and MS Word to manage his company$$s processes and operations. The business of CoolAir

has grown exponentially in last $3$ years. John has contacted you to develop a database system

for his business. In his first couple of interviews with John, you have found out the following

information:

$1$Commissioning means putting the particular job$/$project in actual$/$intended service

$2$This is a fictitious name imagined for academic learning. Any resemblance to any real company is accidental. a$)$ Whenever a customer awards a job, CoolAir creates a unique job$-$number along with

current date and expected date of item. CoolAir provides new ACs as well as services the

existing ones to now a large customer base.

b$)$ For new installations, CoolAir has to design the capacity of the AC to install. For designing

the AC$,$ basic information about the location of installation is required, such as Total area

of cooling in square feet, Number of hours in exposed to Sun, Number of people in the

facility, type of use, such as residential$/$commercial$.$

c$)$ The ACs are identified by a large number of specs but the following are most important. SEER Rating, BTU, System Size in Tons, Decibels, Compressor type, Dimensions

$($LxWXH$),$ and Warranty.

d$)$ For service orders, CoolAir wants to know the basic specifications about the AC$.$ Customers also provide information about symptoms of the problem faced by them $($e$.$g$.$ the

fan is not spinning, I can hear the fan throwing the air but the air is not cool$).$

e$)$ CoolAir employs many individuals with a variety of skills. Each employee is given a

unique nick name. Storing information about employees$$ first name, last name, address,

home phone, mobile phone, email address is necessary because of government regulations.

CoolAir also wants the system to keep track of the skill set of employees that will help

them send the technicians with $$right$$ skills to every job. Knowing skills of employees

is important because service orders by customers typically require specific expertise $($e$.$g$.$

insulation, electrical, air handling unit, ducting, compressor$).$ In addition, it is important

to keep track of licenses $($types$,$ when taken, from where, expiry etc$)$ of employees.

f$)$ CoolAir does offer employment benefits to its employees. These benefits are based on

the length of service, therefore tracking start of service of every employees is required.

g$)$ Employees are paid fixed monthly wages plus performance wages that are are calculated by

multiplying hourly wage with the number of hours spent by employees in servicing$/$repairs

at customers$$ locations. Therefore, CoolAir records the check$-$in and check$-$out times of

service technicians when they visit customers to attend to service calls.

h$)$ There are many AC brands in the market and customers often expect immediate repair

of their ACs especially in the summer months. Therefore, CoolAir holds a good stock

of AC parts that are frequently required. Each part has a name, manufacturer name, a

model number, cost. Model number is unique for all parts.

i$)$ CoolAir invoices customers based on cost of material and labor, including the new installations because every AC job includes labor component. A repair job certainly involves

labor $($no$.$ of hours by technicians$)$ but may also involve material depending on the problem. Each repair job record has a unique job number, the customer$$s name, address,

phone number, date when brought and date when promised delivery.

j$)$ A technician may be assigned to several jobs in a day. To keep track of hours worked by

employees, the labor record has date, begin$-$time, end$-$time, job$-$number, and technician$$s

nick name.

Clearly mark$/$label:

$($a$)$ Entities

$($b$)$ Attributes