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Chapter 7: Problem 40

Develop an ERD to allow us to keep information on a survey. Suppose a survey will have several questions that can be answered true or false. Over a period of time the survey is conducted and there will be several responses.

Short Answer

Expert verified
The ERD includes three main entities ('Survey', 'Question', 'Response') with their attributes, and the relationships between them. Noting that a 'Survey' consists of many 'Questions', and each 'Question' on a 'Survey’ can have multiple 'Responses' is crucial.

Step by step solution

01

Identify Main Entities

The first step is to determine the main entities of the system based on the problem description. In this case, the main entities are: 'Survey', 'Question', and 'Response'.
02

Identify Attributes

Next, determine the attributes for each entity. For 'Survey': survey ID, date, title could be attributes. For 'Question': question ID, content, survey ID (to indicate which survey the question belongs to) could be its attributes. For 'Response': response ID, respondent ID, survey ID, question ID, answer (True/False) could serve as its attributes.
03

Determine Relationships

Then, the relationships betwen the entities need determination. A 'Survey' consists of multiple 'Questions’, this is reflected as a one-to-many relationship between these entities. A 'Response' is given by a respondent to a 'Question' in a 'Survey', hence it has relationships with both 'Survey' and 'Question'. These are also one-to-many relationships since a single survey/question can have multiple responses.
04

Create ERD

Finally, put all these elements together to create the ERD. Entities are represented as rectangles, attributes as ovals, and relationships as diamonds. Make sure to indincate the type of relationship (one-to-one, one-to-many) with the correct notation.

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Most popular questions from this chapter

Assuming you have experience with some database system, what data type would you use for surrogate keys?

Develop an ERD to be used by a company to manage the orders it receives from its customers. Each customer is identified uniquely by a customer id; include the first name, last name, and address for each customer. The company has several products that it stocks and for which customers place orders. Each product has a unique id, unique name, unit price, and a quantity on hand. At any time a customer may place an order which will involve possibly many products. For each product ordered the database must know the quantity ordered and the unit price at that point in time. If the customer does this through a phone call then an employee is involved in the call and will be responsible for the order from the company side. Some orders are placed via the internet. For each order an order number is generated. For each order the database must keep track of the order number, the date the order was placed and the date by which the customer needs to receive the goods.

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