Database Reference
In-Depth Information
3.5 Summary
In this chapter, we have discussed tables, table normalization, and transferring a data model
to a relational database. At the beginning of the chapter, the concepts of tables and functional
dependencies were introduced. We discussed the table components and how to link two tables
with a shared column. he deinitions of primary keys and foreign keys were presented. Before
a data model can be converted to a relational database, you need to properly normalize the
table structures. During the normalization process, you may need to modify the initial E-R
model. You may need to add or remove some of the entities or attributes based on the result of
normalization. In a normalization process, a table is split to eliminate modiication anomalies.
Step by step, you learned in detail about the normal forms 1NF, 2NF, 3NF, BCNF, 4NF, and
DK/NF. Denormalization was also discussed in this chapter. After the data model has been
modiied based on the result of the normalization, you are ready to convert the data model to
a relational database. In this chapter, you have learned how to represent entities and relation-
ships with relations and pairs of primary and foreign keys. In the hands-on practice section,
you learned how to create tables on Windows Azure SQL Database and how to enter data into
tables manually.
Review Questions
1. What are the conditions for a table to be a relation?
2. How do you link a table to another table?
3. What is functional dependency? Give an example of functional dependency.
4. What is a primary key?
5. What is a foreign key?
6. Describe update anomalies by using an example.
7. Describe insertion anomalies by using an example.
8. Describe deletion anomalies by using an example.
9. Why do tables need to be normalized?
10. Why is the highest-level normalization not always desirable?
11. What are the requirements for 1NF?
12. What are the requirements for 2NF?
13. What is 3NF?
14. What is BCNF?
15. List the naming rules used in this topic.
16. What do you do with the delimiters “ ” and []?
17. When a name starts with the symbol @, what does the symbol represent?
18. Use an example to explain how to represent a nonidentifying relationship with tables.
19. Use an example to represent a nonspeciic relationship with tables.
20. How do you implement a referential constraint?
