Answered step by step
Verified Expert Solution
Question
1 Approved Answer
READ BEFORE SOLVING. For each question 1 - 5 read the questions carefully Make a seperate diagram for each questions. I will up vote. Thanks
READ BEFORE SOLVING. For each question read the questions carefully
Make a seperate diagram for each questions. I will up vote. Thanks
Consider a database containing information about power outages.
Create entities and relationships as appropriate for each independent situation described below.
Read This! Information that is true for ALL of the following ER diagrams: Each power outage has a unique outage identifying number. Each outage also has a start time, a cause, and a status, For each of the following situations, draw an ER diagram that describes it Consider each situation independently. Multiple situations means multiple, separate ER diagrams in a correct homework solution. Information in parentheses is simply information. Information in parentheses does not affect the ER diagrams, but may help you understand the real world context of the question. Note: I may have "fudged" the truth a bit, on these questions, to make good homework questions. Draw the ER diagrams for the situations as described.
Each power outage may affect multiple streets, and streets can be affected by multiple power outages. For streets, the database stores an identifying street number. The database also stores the street name, the street city many cities have a street named "Main" and the latitudelongitude coordinates of each end of the street. Two pairs of latitudelongitude numbers, one for each end. It is possible for an outage to affect no streets, and for a street to have no outages on it
The database tracks repair teams. Each team has a team identifying number, a contact phone number, a repair truck number, and a description. Each team might be working on fixing one outage, or none. An outage might have no repairs working on it or one, or many teams.
The database can track notes about each outage. Each note has a timestamp, the text of the note, and the employee ID number of the person entering the note. A sample note might record that, at pm employee wrote, "cutting up fallen tree branch". The notes help the power company track the progress of an outage repair. Each note pertains to exactly one outage. There is no unique identifier for every note. A note belongs to only one outage. For a particular outage, each note for that outage will have a different timestamp.
Some outages are brownouts; some outages are power station failures. For brownouts, the database stores the voltage of the power supply during the brownout. In a brownout some power is flowing, but not the full and proper amount. Some outages are caused by a power station going offline. For those outages, the database stores the street address of the affected power station. A power station outage is never a brownout, and a brownout cannot be caused by a power station outage. Power station outages cause blackouts, severe ones.
The database tracks the supplies used to repair an outage. For each supply item, the database stores a supply identifier unique a name, a pricecost and a size. Many supply items might be used to fix an outage, and many outages might require the same supply item to fix them. A replacement piece of power line wire, for example. For any particular supply item and an outage it helps repair, the database tracks how many of the items were used. For example, a particular outage repair might require replacement power pole, replacement chunks of power wire, and new screws.
Step by Step Solution
There are 3 Steps involved in it
Step: 1
Get Instant Access to Expert-Tailored Solutions
See step-by-step solutions with expert insights and AI powered tools for academic success
Step: 2
Step: 3
Ace Your Homework with AI
Get the answers you need in no time with our AI-driven, step-by-step assistance
Get Started