What is a surrogate key, and when should you use one?

4 years ago
Database Management System

New Tables

A surrogate key is an artificial PK introduced by the designer with the purpose of simplifying the assignment of primary keys to tables. Surrogate keys are usually numeric, they are often automatically generated by the DBMS, they are free of semantic content (they have no special meaning), and they are usually hidden from the end users.

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Bijay Satyal
Bijay Satyal
Oct 23, 2021
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1. Given the sample records in the CHARTER table shown in Table P6.11, do the following:

2. The manager of a consulting firm has asked you to evaluate a database that contains the table structure shown in Table P6.10.

3. Suppose that you have been given the table structure and data shown in Table 6.9, which was imported from an Excel spreadsheet. The data reflect that a professor can have multiple advisees, can serve on multiple committees, and can edit more than one journal.

4. Use the dependency diagram shown in Figure 6.8 to work the following problems.

5. Suppose you are given the following business rules to form the basis for a database design. The database must enable the manager of a company dinner club to mail invitations to the club’s members, to plan the meals, to keep track of who attends the dinners, and so on.

6. The table structure shown in Table P6.6 contains many unsatisfactory components and characteristics. For example, there are several multivalued attributes, naming conventions are violated, and some attributes are not atomic.

7. To keep track of office furniture, computers, printers, and so on, the FOUNDIT company uses the table structure shown in Table P6.5.

8. Using the STUDENT table structure shown in Table P6.4, do the following:

9. Using the INVOICE table structure shown in Table P6.3, do the following

10. Using the descriptions of the attributes given in the figure, convert the ERD shown in Figure P6.2 into a dependency diagram that is in at least 3NF.

11. Using the descriptions of the attributes given in the figure, convert the ERD shown in Figure P6.1 into a dependency diagram that is in at least 3NF.

12. A table is in 3rd _ normal form when it is in 2nd normal form and there are no transitive dependencies.

13. Suppose that someone tells you that an attribute that is part of a composite primary key is also a candidate key. How would you respond to that statement?

14. How would you describe a condition in which one attribute is dependent on another attribute when neither attribute is part of the primary key?

15. Why is a table whose primary key consists of a single attribute automatically in 2NF when it is in 1NF?

16. What three data anomalies are likely to be the result of data redundancy? How can such anomalies be eliminated?

17. What is a partial dependency? With what normal form is it associated?

18. The dependency diagram in Figure Q6.8 indicates that a patient can receive many prescriptions for one or more medicines over time. Based on the dependency diagram, create a database whose tables are in at least 2NF, showing the dependency diagram for each table.

19. The dependency diagram in Figure Q6.7 indicates that authors are paid royalties for each book that they write for a publisher. The amount of the royalty can vary by author, by book, and by edition of the book.

20. Given the dependency diagram shown in Figure Q6.6, answer items 6a-6c:

21. When is a Table in BCNF?

22. When is a table in 3NF?

23. When is a table in 2NF?

24. When is a table in 1NF?

25. What is normalization?

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