Chapter 2: The Relational Model 1: Introduction, QBE, and Relational Algebra
True / False
1. A relational database handles entities, attributes, and relationships by storing each entity in its own table.
a.
True
b.
False
True
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2. The attributes of an entity become the fields or columns in a table.
a.
True
b.
False
True
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3. Each column in a table should have a unique name, and entries in each column should all “match” this column name.
a.
True
b.
False
True
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4. In a relation, the order of the columns is important.
a.
True
b.
False
5. In a relation, the order of rows is important.
a.
True
b.
False
6. A relational database is a collection of relations.
a.
True
b.
False
True
1
7. An unnormalized relation is a table that has more than one row.
a.
True
Chapter 2: The Relational Model 1: Introduction, QBE, and Relational Algebra
b.
False
8. A column whose value uniquely identifies a given row in the table is the secondary key.
a.
True
b.
False
9. A query is a question represented in a way that the DBMS can recognize and process.
a.
True
b.
False
True
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10. QBE is a visual approach to writing queries.
a.
True
b.
False
True
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11. Access automatically adds double quotation marks around values in the design grid that are formatted as
Short Text fields when you run the query or move the insertion point to another cell in the design grid.
a.
True
b.
False
True
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12. The comparison operators are +, *, %, and /.
a.
True
b.
False
13. The comparison operators are also known as relational operators.
a.
True
b.
False
True
14. In an AND criterion, the overall criterion is true if either of the individual criteria is true.
a.
True
b.
False
15. The concept of grouping means that statistics will be calculated for individual records.
a.
True
b.
False
16. A relation is a(n) ____.
a.
attribute
b.
column
c.
field
d.
table
d
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17. Based on the statement below, which of the following is the primary key?
Rep (RepNum, LastName, FirstName, Street, City, State, PostalCode Commission, Rate)
a.
RepNum
b.
LastName
c.
FirstName
d.
State
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18. When duplicate column names exist in a database and you need to indicate the column to which you are referring,
____.
a.
do not use these two tables together
b.
do not use the column names in the same statement
c.
write both the table name and the column name, separated by a period
d.
write the table name only
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19. Rows are also called ____.
a.
fields
b.
columns
c.
tuples
d.
attributes
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20. The ____ key of a table is the column or collection of columns that uniquely identifies a given row in that table.
a.
primary
b.
secondary
c.
foreign
d.
minor
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21. The compound criteria (conditions) are created by using ____.
a.
AND, OR
b.
AND, NOR
c.
OR, NOT
d.
NOT, ONLY
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22. Count, Sum, Avg, Max, and Min are a few of the built-in statistics or ____ functions that can be used in a query.
a.
accumulated
b.
allowed
c.
primary
d.
aggregate
d
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23. If you are sorting records by more than one field, the more important field is called the ____.
a.
primary sort key
b.
secondary sort key
c.
maximum sort key
d.
minor sort key
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Chapter 2: The Relational Model 1: Introduction, QBE, and Relational Algebra
24. A query that changes data is a(n) ____ query.
a.
addition
b.
update
c.
update
d.
select
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25. A ____ query creates a new table using the query results.
a.
new-table
b.
make-table
c.
create-table
d.
merge-table
b
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26. The ____ command within relational algebra takes a vertical subset of a table.
a.
SELECT
b.
DELETE
c.
PROGRAM
d.
PROJECT
d
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27. Based on the Customer table below, which command lists all information from the table concerning customer 260?
CustomerNum CustomerName Street City State PostalCode
126 Toys Galore 28 Laketon St. Fulton CA 90085
260 Brookings Direct 452 Columbus Dr. Grove CA 90092
a.
SELECT Customer 260 GIVING Answer
b.
SELECT Customer WHERE CustomerNum=260 GIVING Answer
c.
SELECT Customer WHERE Customernum=’260’ GIVING Answer
d.
SELECT Customer WHERE CustomerName=’260’ GIVING Answer
b
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28. The ____ command within relational algebra includes the word OVER followed by a list of the columns to be
included.
a.
DELETE
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Chapter 2: The Relational Model 1: Introduction, QBE, and Relational Algebra
b.
PROJECT
c.
INTERSECT
d.
UNION
b
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29. Which operation will allow you to extract data from more than one table?
a.
Select
b.
Merge
c.
Project
d.
Join
d
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30. You can restrict the output from a join to include only certain columns by using the ____ command.
a.
DELETE
b.
UNION
c.
PROJECT
d.
INTERSECT
1
31. Two tables are considered to be ____ compatible if they have the same number of columns and their corresponding
columns represent the same type of data.
a.
union
b.
intersection
c.
difference
d.
product
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32. The ____ operation is performed by the SUBTRACT command in relational algebra.
a.
union
b.
difference
c.
product
d.
intersection
b
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33. The ____ operator is used to concatenate every row in the first table with every row in the second table.
Chapter 2: The Relational Model 1: Introduction, QBE, and Relational Algebra
a.
union
b.
difference
c.
product
d.
intersection
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34. The product of two tables is also called the ____ product.
a.
Cartesian
b.
aggregate
c.
Cathode
d.
exponential
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35. Using the product operator, if table A has 4 rows and table B has 4 rows, the number of rows in the product of these
two tables is ____.
a.
4
b.
8
c.
16
d.
256
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Completion
36. A(n) ____________________ database is a collection of tables.
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37. The relationships between tables are handled through ____________________ columns.
common
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38. Multiple entries in tables are often called ____________________.
repeating groups
1
39. When a structure satisfies all the properties of a relation except for the first item—in other words, some entries contain
repeating groups and thus are not single-valued—it is referred to as a(n) ____________________.
Chapter 2: The Relational Model 1: Introduction, QBE, and Relational Algebra
40. Columns in a table are often called ____________________.
41. Conditions that data must satisfy are called ____________________.
42. A(n) ____________________ field is a field that is the result of a calculation using one or more existing fields.
43. To list the records in a query’s results in a particular order, you need to ____________________ the records.
44. The field on which records are sorted is called the ____________________.
45. ____________________ is a theoretical way of manipulating a relational database.
46. Provide a definition for the term relation.
47. What is the difference between an AND criterion and an OR criterion? How is each criterion created in QBE?
48. List at least six of the aggregate functions available in Access. Explain how to use any of these functions in a query.
49. Discuss the difference between the major sort key and the minor sort key.
50. Explain what relational algebra is and how it is used.