murachs_php_4E_chapter16

Chapter 16: How to design a database Murach's PHP and MySQL (4th Ed.) MULTIPLE CHOICE 1. To model a database on a real-world system, you typically represent each real-world entity as a/an ________________. a. object c. table b. class d. data element ANS: C 2. If two tables have a one-to-many relationship, you may need to add a ________________ column to the table on the “many” side. a. primary key c. linking key b. foreign key d. index ANS: B 3. If two tables have a many-to-many relationship, you need to define a/an ________________ table that relates their rows. a. linking c. central b. correlation d. relative ANS: A 4. Referential integrity means that the ________________ between tables are maintained correctly. a. foreign keys c. relationships b. primary keys d. indexes ANS: C 5. To normalize a data structure, you a. apply the steps for designing a data structure b. identify the data elements c. identify the tables and assign columns d. apply the normal forms in sequence ANS: D 6. SELECT statements for data structures that are normalized to the fourth or fifth normal form typically require more ________________ than denormalized data structures. a. subqueries c. WHERE clauses b. joins d. grouping ANS: B 7. To speed performance when searching and joining tables, you can use ____________. a. primary keys c. joins b. foreign keys d. indexes

ANS: D 8. With recent versions of MySQL, you can use ________________ constraints to enforce referential integrity. a. referential c. foreign key b. relative d. primary key ANS: C 9. Which of the following diagrams best represents the relationship between a table of customers and a table of orders placed by customers? a. b. c. d. ANS: B 10. Every row in a table should be uniquely identified by a ________________ key. a. primary c. confusing b. parameterized d. imaginary ANS: A 11. Which of the following diagrams best represents the relationship between a table of students and a table of classes for which the student is registered? a. b.

a. the largest practical components b. the smallest practical components c. components that can be easily parsed each time you use them ANS: B 15. Which of the following ensures that relationships between tables are maintained correctly? a. metadata c. Structured Query Language (SQL) b. referential integrity d. flux capacitor ANS: B 16. A(n) ________________ provides a way for a database management system to locate information more quickly. a. anomaly c. slow computer b. index d. large monitor ANS: B 17. To be in the first normal form, each cell in a table must contain a. a unique value c. a single, scalar value b. a non-unique value d. a non-redundant value ANS: C 18. Which of the following is a formal process used to separate data into related tables to avoid data redundancy? a. normalization c. referential integrity b. serialization d. data mining ANS: A 19. Which of the following does NOT violate the referential integrity of a database? a. inserting a new row into a table with a foreign key that doesn’t match a primary key in the related table b. updating a foreign key with a value that doesn’t match a primary key in the related table c. updating a primary key in a primary key table without also updating the foreign keys for the related rows in all related tables d. deleting a row in a foreign key table without deleting the related row in the related primary key table ANS: D 20. To apply the second normal form, you move columns that don’t depend on the entire primary key to another table and establish a relationship between the two tables. This a. reduces redundancy but makes maintenance more difficult b. reduces redundancy and makes maintenance easier c. increases redundancy but makes maintenance easier d. increases redundancy but makes the data more consistent ANS: B

21. To be in the third normal form, each non-key column a. must depend only on the primary key b. must not depend on the primary key c. must depend on the foreign key d. must depend on the index ANS: A 22. Denormalization typically results in all but one of the following. Which one is it? a. larger tables c. more complicated SQL coding b. redundant data d. reduced performance ANS: C 23. It is usually not a good practice to create an index for a column when a. the column is a foreign key b. the column is frequently updated c. the column is frequently used in search conditions or joins d. the column contains a large number of unique values ANS: B 24. Which type of key consists of more than one field? a. foreign key c. compartmentalized key b. alphabetized key d. composite key ANS: D 25. A database is typically considered normalized if it is in ________________ normal form. a. paranormal c. third b. second d. first ANS: C 26. For a table to be in ___________ normal form, every non-key column must depend only on the primary key. a. third c. first b. second d. zero ANS: A 27. ________________ can result in larger tables, redundant data, and reduced performance. a. Normalization c. Refactoring b. Denormalization d. Indexing ANS: B 28. If two tables have a one-to-many relationship, you may need to add a _____________ column to the table on the “many” side. a. foreign key c. invisible key b. referential constraint d. numeric index