Question

Q1.Generate an ERD diagram for the following scenario using Lucidchart. I need to know what the diagram should look like.

(I am not sure there should be any kind of relationship between entities.)

Scenario: Southlands Electric

Southlands Electric wishes to create a database with the following information:

Customer with attributes Customer ID, Name, Address (Street, City, State, Zip Code), and Telephone
Location with attributes Location ID, Address (Street, City, State, Zip Code), and Type (values of Business or Residential)
Rate with attributes Rate Class and RatePerKWH
After interviews with the owners, you have come up with the following business rules:

Customers can have one or more locations
Each location can have one or more rates, depending on the time of day

Answer 1

Before drawing the diagram, let's see the various entities and the relationships between them.
The three entities are: Customer, Location and Rate. Customer's primary key is CustomerID and Location's primary key is LocationID.
Customer and Location have the relationship "Owns". Location and Rate have the relationship "Charges".
Now as per the question, a customer can have one or more locations, therefore Customer-Location relationship is one-to-many. And also that a customer should have at least one location.
(Explanation: For a customer to be in the company's database, he/she should own at least one place with a connection from Southlands Electric. He/She can also have multiple places or houses with an electricity connection from the company. It is perfectly possible that the billing address of the customer or the address at which he resides and the address of the place with electricity connection are different )
Also given, each location can have one or more rates. It is also possible that many locations have the same rate, for example- locations of the same type and in the same area would have the same rate. Hence the relationship Location-Rate is many-to-many. Also, each location should have at least one rate.
(Explanation: Each location should have at least one rate slab associated with it for the bill to be calculated).
So the ER diagram would look like this: (I have not used Lucidchart to draw these)

In another notation:

Although it’s not given specifically but there should also be a Time attribute associated with the relationship “Charges”.
Please let us know if you have any further doubts.