Preview Extract
Chapter 14: Using Relational Databases
TRUE/FALSE
1. Database software recognizes the distinction between text and numeric data.
Answer: True
2. In some database software packages, such as Microsoft Access, you indicate a primary key
simply by selecting a column name and clicking a button that is labeled with a key icon.
Answer: True
3. Some database designers insert an exclamation point after the key instead of underlining it.
Answer: False
4. Entering data into an existing table is not difficult, but it requires a good deal of time and
accurate typing.
Answer: True
5. In many database systems, some “deleted” records are not physically removed, but they are
just marked as deleted so that they will not be used to process active records.
Answer: True
6. Structured Query Language is a commonly used language for accessing data in database
tables.
Answer: True
7. A common reason you create a one-to-one relationship is security.
Answer: True
8. Normalization involves altering a table so that it satisfies one or more of four normal
forms, or sets of rules for constructing a well-designed database.
Answer: False
9. 3NF requires that a table be in 2NF and have transitive dependencies.
Answer: False
10. Database software provides the means to ensure that data integrity is enforced.
Answer: True
MULTIPLE CHOICE
1. In a database, the files often are called ____ because you can arrange their contents in rows
and columns.
a. sheets
b. pages
c. forms
d. tables
Answer: D
2. A key that is constructed from multiple columns is called a compound key or ____ key.
a. composite
b. combined
c. joined
d. joint
Answer: A
3. When a field in a database contains a null value, it means that ____.
a. the field holds zeros
b. the field holds spaces
c. no data has been entered in the field
d. the field holds asterisks
Answer: C
4. If an employee record contains both a company-assigned employee ID and a Social
Security number, then both columns are ____ keys.
a. primary
b. candidate
c. secondary
d. foreign
Answer: B
5. After you choose a primary key from among candidate keys, the remaining candidate keys
become ____ keys.
a. primary
b. secondary
c. alternate
d. candidate
Answer: C
6. Depending on the software you use, you might create a query by filling in blanks in a
process called ____.
a. query by example
b. query by reference
c. query by demonstration
d. query by comparison
Answer: A
7. The basic form of the SQL statement that retrieves selected records from a table is ____.
a. GET-FROM-WHERE
b. SELECT-FROM-WHERE
c. RETRIEVE-FROM-WHERE
d. SELECTION-FROM-WHERE
Answer: B
8. In database management systems, a particular way of looking at a database is sometimes
called a(n) ____.
a. segment
b. identity
c. view
d. value
Answer: C
9. A symbol that means “any” or “all” is known as a ____.
a. placeholder
b. token
c. substitution
d. wildcard
Answer: D
10. Connecting two tables based on the values in a common column is called a(n) ____
operation.
a. union
b. join
c. intersection
d. liberation
Answer: B
11. A ____ relationship is the most common type of relationship between tables.
a. one-to-many
b. one-to-one
c. many-to-one
d. many-to-many
Answer: A
12. A(n) ____ key is a column that is not a key in a table, but it contains an attribute that is a
key in a related table.
a. alternate
b. candidate
c. foreign
d. primary
Answer: C
13. ____ is the unnecessary repetition of data.
a. Data duplication
b. Data replication
c. Data normalization
d. Data redundancy
Answer: D
14. An ____ is an irregularity in a database’s design that causes problems and
inconveniences.
a. inversion
b. inference
c. anomaly
d. abstraction
Answer: C
15. A table that contains repeating groups is ____.
a. unnormalized
b. normalized
c. simplified
d. non-normalized
Answer: A
16. A ____ is a subset of rows in a database table that all depend on the same key.
a. complete group
b. flattened group
c. repeating group
d. normalized group
Answer: C
17. When you combine two columns to create a compound key, you are ____ the columns.
a. splitting
b. converting
c. joining
d. concatenating
Answer: D
18. Database developers also refer to operations or transactions as ____ transactions when
they appear to execute completely or not at all.
a. coupled
b. atomic
c. decoupled
d. nominal
Answer: B
19. A transitive ____ occurs when the value of a nonkey attribute determines, or predicts, the
value of another nonkey attribute.
a. conversion
b. recursion
c. dependency
d. anomaly
Answer: C
20. To ____ a table is to reduce it to a lower normal form by placing some repeated
information back into the table.
a. denormalize
b. normalize
c. flatten
d. compose
Answer: A
21. A database has ____ when it follows a set of rules that makes the data accurate and
consistent.
a. transparent integrity
b. data availability
c. data integrity
d. data security
Answer: C
22. A ____ is a mechanism that prevents changes to a database for a period of time.
a. flag
b. lock
c. permission
d. transaction
Answer: B
23. ____ techniques include storing and verifying passwords or even using physical
characteristics, such as fingerprints or voice recognition, before users can view data.
a. Authorization
b. Data conversion
c. Data normalization
d. Authentication
Answer: D
24. The ____ assigned to a user indicate which parts of the database the user can view,
modify, or delete.
a. permissions
b. controls
c. locks
d. attributes
Answer: A
25. ____ is the process of coding data into a format that human beings cannot read.
a. Integrity
b. Availability
c. Encryption
d. ACID
Answer: C
COMPLETION
1. ____________________ are formed from groups of related fields.
Answer: Records
2. ____________________ are composed of associated records.
Answer: Falseiles
3. A primary key should be ____________________, meaning that a value does not change
during normal operation.
Answer: immutable
4. The column on which tables are connected is the ____________________ column.
Answer: join
5. A(n) ____________________ is a long-term database lock required when users want to
maintain a consistent view of their data while making modifications over a long transaction.
Answer: persistent lock
MATCHING
Match each term with a statement below.
1. The smallest usable units of data a. database
2. Represent a piece of information b. relational database
3. Holds a group of files that an organization needs to support its applications c. recovery
4. A value that uniquely identifies a record d. characters
5. A group of database tables from which you can make connections between columns e.
primary key
6. A question using the syntax that the database software can understand f. query
7. The connection between two tables g. batch
8. The process of returning the database to a correct form that existed before an error
occurred h. relationship
9. Occurs when two database users need to modify the same record at the same time i.
concurrent update problem
10. A group of transactions applied all at once j. fields
1. Answer: D
2. Answer: J
3. Answer: A
4. Answer: E
5. Answer: B
6. Answer: F
7. Answer: H
8. Answer: C
9. Answer: I
10. Answer: G
SHORT ANSWER
1. Discuss how to create databases and design tables.
Answer: Creating a useful database requires planning and analysis. You must decide what
data will be stored, how that data will be divided between tables, and how the tables will
interrelate. Before you create any tables, you must create the database itself. With most
database software packages, creating the database that will hold the tables requires nothing
more than naming it and indicating the physical location, perhaps a hard disk drive, where the
database will be stored. When you save a table, it is conventional to provide a name that
begins with the prefix “tbl”—for example, tblCustomers. Your databases often become filled
with a variety of objects—tables, forms for data entry, reports that organize the data for
viewing, queries that select subsets of data for viewing, and so on. Using naming
conventions, such as beginning each table name with a prefix that identifies it as a table,
helps you keep track of the objects in your system.
Before you can enter any data into a database table, you must design the table. It is important
to think carefully about the original design of a database. After the database has been created
and data has been entered, it could be difficult and time consuming to make changes. At
minimum, designing a table requires that you choose columns for it and then provide names
and data types for each column.
2. Discuss the use of null values within a database table.
Answer: Unassigned variables within computer programs might be empty (containing a null
value), or might contain unknown or garbage values. Similarly, columns in database tables
might also contain null or unknown values. When a field in a database contains a null value,
it does not mean that the field holds a 0 or a space; it means that no data has been entered for
the field at all. Although null and empty are used synonymously by many database
developers, the terms have slightly different meanings to some professionals, such as Visual
Basic programmers.
3. List two examples of primary keys.
Answer: Typical examples of primary keys include:
A student ID number in a table that contains college student information
A part number in a table that contains inventory items
A state abbreviation in a table that contains sales information for each state in the United
States
4. List three reasons why a primary key is important.
Answer: The primary key is important for several reasons:
You can configure your database software to prevent multiple records from containing the
same value in this column, thus avoiding data-entry errors.
You can sort your records in this order before displaying or printing them.
You use the primary key column when setting up relationships between this table and others
that will become part of the same database.
You need to understand the concept of the primary key when you normalize a database.
5. Discuss a shorthand way to describe a table.
Answer: A shorthand way to describe a table is to use the table name followed by parentheses
containing all the field names, with the primary key underlined. Thus, when a table is named
tblStudents and contains columns named idNumber, lastName, firstName, and
gradePointAverage, and idNumber is the key, you can reference the table using the following
notation:
tblStudents(idNumber, lastName, firstName, gradePointAverage)
Although this shorthand notation does not provide information about data types or range
limits on values, it does provide a quick overview of the table’s structure. The key does not
have to be the first attribute listed in a table reference, but frequently it is.
6. Discuss how to sort the records in a table.
Answer: Database management software generally allows you to sort a table based on any
column, letting you view the data in the way that is most useful to you. For example, you
might want to view inventory items in alphabetical order, or from the most to least expensive.
You can also sort by multiple columns—for example, you might sort employees by first
name within last name (so that Aaron Black is listed before Andrea Black), or by department
within first name within last name (so that Aaron Black in Department 1 is listed before
another Aaron Black in Department 6). When sorting records on multiple fields, the software
first uses a primary sort—for example, by last name. After all records with the same primary
sort key are grouped, the software sorts by the secondary key—for example, first name.
After rows are sorted, they usually can be grouped. For example, you might want to sort
customers by their zip code, or employees by the department in which they work; in addition,
you might want counts or subtotals at the end of each group. Database software allows you to
create displays in the formats that suit your needs.
7. List the three types of relationships that can exist between tables.
Answer: One-to-many
Many-to-many
One-to-one
8. List and explain the three normal forms.
Answer: The three normal forms are:
• First normal form, also known as 1NF, in which you eliminate repeating groups
• Second normal form, or 2NF, in which you eliminate partial key dependencies
• Third normal form, or 3NF, in which you eliminate transitive dependencies
9. List four major issues with database performance and security.
Answer: The major issues include:
• Providing data integrity
• Recovering lost data
• Avoiding concurrent update problems
• Providing authentication and permissions
• Providing encryption
10. Discuss the issue of recovering lost data.
Answer: An organization’s data can be destroyed in many ways—legitimate users can make
mistakes, hackers or other malicious users can enter invalid data, and hardware problems can
wipe out records or entire databases. Recovery is the process of returning the database to a
correct form that existed before an error occurred.
Periodically making a backup copy of a database and keeping a record of every transaction
are two of the simplest approaches to recovery. When an error occurs, you can replace the
database with an error-free version that was saved at the last backup. Usually, changes to the
database, called transactions, have occurred since the last backup; if so, you must then
reapply those transactions. Many organizations keep a copy of their data off-site (sometimes
hundreds or thousands of miles away) so that if a disaster such as a fire or flood destroys
data, the remotely stored copy can serve as a backup.
Test Bank for Programming Logic and Design
Joyce Farrell
9781111969752, 9788131525906, 9781111825959
