ch9 questions

Question 1

What does the word relationship mean in reference to a relational database?

Answer 1

The term relationship refers to the connection between two pieces of data that have some association, such as a book and its author, or a book and the customer who bought the book. A relational database such as MySQL specializes in storing and retrieving such relations.

Question 2

What is the term for the process of removing duplicate data and optimizing tables?

Answer 2

Normalization

Question 3

What are the three rules of the First Normal Form?

Answer 3

The three rules of the First Normal Form are:

• There should be no repeating columns containing the same kind of data.
• All columns should contain a single value.
• There should be a primary key to uniquely identify each row.

Question 4

How do you make a table satisfy the Second Normal Form?

Answer 4

To satisfy Second Normal Form, columns whose data repeats across multiple rows should be removed to their own tables.

Question 5

What do you put in a column to tie together two tables that contain items having a one-to-many relationship?

Answer 5

In a one-to-many relationship, the primary key from the table on the “one” side must be added as a separate column (a foreign key) to the table on the “many” side.

Question 6

How can you create a database with a many-to-many relationship?

Answer 6

To create a database with many-to-many relationship, you create an intermediary table containing keys from two other tables. The other tables can then reference each other via the third.

Question 7

What commands initiate and end a MySQL transaction?

Answer 7

BEGIN and COMMIT

Question 8

What feature does MySQL provide to enable you to examine how a query will work in detail?

Answer 8

EXPLAIN

Question 9

What command would you use to back up the database publications to a file called publications.sql?

Answer 9

mysqldump -u user -ppassword -D publications > publications.sql