Chapter 1 Solutions
1. What is the purpose of an E-R Model? To identify the entities about which the database should store data, and the relationship among those entities.
2. What is an entity? An entity is any person, place, or thing having attributes, or characteristics, of interest to the organization.
3. Give an example of three entities that might exist in a database for a medical office and some of the attributes that would be stored in a table for each entity. Doctor – name, address, Social Security Number, medical ID number; Patient – name, address, Social Security Number, insurance policy information, medical history; Appointment – date, time, patient, doctor.
4. Define a one-to-many relationship. An occurrence of data in one entity results in only one occurrence of data in the other entity.
5. Discuss the problems that can be caused by data redundancy. Can create data anomalies or inconsistencies in the data making it unreliable.
6. Explain the role of a primary key. The primary key is used to uniquely identify each row in a table.
7. Describe how a foreign key is different from a primary key. A foreign key is used to reference or join data in different tables. In most cases, the foreign key references a primary key in another table. In a one-to-many relationship, the foreign key is stored in the “many” entity.
8. List the steps of the normalization process. First, a primary key is identified and any repeating groups are identified. Then any partial dependencies are eliminated. Finally, any transitive dependencies are eliminated.
9. What type of relationship cannot be stored in a database? Why? A many-to-many relationship cannot be stored in a database since there would be no way to restructure or re-join the data correctly.
10. Identify at least three reasons an organization might analyze historical sales data stored in its database. Answers will vary - To determine the necessary inventory levels to support sales fluctuations, project employee scheduling requirements, determine appropriate marketing campaigns based upon historic purchasing patterns.
1. Which tables and fields would you access to determine which books have been purchased by a customer over the last year? CUSTOMERS: customer#, ORDERS: order#, orderdate, customer#; ORDERITEMS: order#, ISBN; BOOKS: ISBN, title
2. How would you determine which orders have not yet been shipped to the customer? Identify all orders that do not have an entry for the date shipped.
3. If management needed to determine which book category generated the most sales for last month, which tables and fields would be consulted to derive this information? ORDERS: orderdate, order#; ORDERITEMS: order#, ISBN, quantity; BOOKS: ISBN, retail
4. How would you determine how much profit was generated from orders placed this month? Determine the amount of profit generated by each book (Retail-Cost), multiply the profit for each book by the quantity sold last month, then total the amount of profit generated by each book.
5. If a customer inquired about a book written in 1999 by an author named Thompson, which access path (tables and fields) would you need to follow to find the list of books meeting the customer’s request? AUTHOR: Lname, AuthorID; BOOKAUTHOR: AuthorID, ISBN; BOOKS: ISBN, Pubdate. 6. A college needs to track placement test scores for all incoming students. Each student may take a variety of tests including English and Math. Some students will not be required to take the placement tests due to previous course work.
7. Every employee in a company is assigned to one department. Every department can contain many employees....
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