Deck 2: The Relational Model 1: Introduction, QBE, and Relational Algebra

Question 1

Rows are also called ____.

A)fields
B)tuples
C)columns
D)attributes

Answer 1

B

Question 2

The attributes of an entity become the rows or records in a table.

Answer 2

False

Question 3

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 the table name only
D)write both the table name and the column name,separated by a period

Answer 3

D

Question 4

A relation is essentially just a two-dimensional table.

Question 5

A relational database is a collection of relations.

Question 6

The comparison operators are also known as relational operators.

Question 7

In a relation,the order of rows is important.

Question 8

Based on the statement below,which of the following is the primary key? Part (PartNum,Description,OnHand,Class,Warehouse,Price)

A)PartNum
B)Description
C)Class
D)Warehouse

Question 9

A relation is a(n) ____.

A)attribute
B)column
C)field
D)table

Question 10

Access automatically adds double quotation marks around values in the design grid that are formatted as Text fields when you run the query or move the insertion point to another cell in the design grid.

Question 11

In a relation,the order of the columns is immaterial.

Question 12

When a field name contains spaces or SQL reserved words,you must enclose the field name in curly braces ({}).

Question 13

QBE is a visual approach to writing queries.

Question 14

In an OR criterion,the overall criterion is true if either of the individual criteria is true.

Question 15

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

Question 16

The concept of grouping means that statistics will be calculated for individual records.

Question 17

A relational database handles entities,attributes,and relationships by storing each entity in its own table.

Question 18

The secondary key provides an important way of distinguishing one row in a table from another.

Question 19

The comparison operators are +,*,%,and /.

Question 20

An unnormalized relation is a table that has more than one row.

Question 21

The compound criteria (conditions) are created by using ____.

A)AND or NOR
B)AND or OR
C)OR or NOT
D)NOT or ONLY

Question 22

If you are sorting records by more than one field,the more important field is called the ____.

A)maximum sort key
B)secondary sort key
C)primary sort key
D)minor sort key

Question 23

The ____ operator is performed by the SUBTRACT command in relational algebra.

A)union
B)intersection
C)product
D)difference

Question 24

Based on the Customer table below,which command lists all information from the table concerning customer 524? CustomerNum CustomerName Street City State Zip
462 Bargains Galore 3829 Central Grove FL 33321
524 Kline's 838 Ridgeland Filmore FL 33336

A)SELECT Customer WHERE CustomerNum=524 GIVING Answer
B)SELECT Customer 524 GIVING Answer
C)SELECT Customer WHERE CustomerNum='524' GIVING Answer
D)SELECT Customer WHERE CustomerName='524' GIVING Answer

Question 25

Which operation will allow you to extract data from more than one table?

A)Select
B)Join
C)Project
D)Merge

Question 26

The relationships between tables are handled through ____________________ columns.

Question 27

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

Question 28

With ____________________,users ask their questions by entering column names and other criteria using an on-screen grid,and data that appears on the screen in tabular form.

Question 29

If each sales rep is related to the many customers he or she represents,and each customer is related to the one sales rep who represents it,then there is a(n) ____________________ relationship between sales reps and customers.

Question 30

The ____ operator is used to concatenate every row in the first table with every row in the second table.

A)union
B)difference
C)product
D)intersection

Question 31

The ____ command within relational algebra includes the word OVER followed by a list of the columns to be included.

A)DELETE
B)PROJECT
C)INTERSECT
D)UNION

Question 32

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) ____________________.

Question 33

A ____ query creates a new table using the query results.

A)make-table
B)new-table
C)create-table
D)merge-table

Question 34

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

Question 35

A query that changes data is a(n) ____ query.

A)addition
B)update
C)update
D)select

Question 36

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

Question 37

The ____ command within relational algebra takes a vertical subset of a table.

A)SELECT
B)DELETE
C)PROGRAM
D)PROJECT

Question 38

Columns in a table are often called attributes or ____________________.

Question 39

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)aggregate
C)primary
D)allowed

Question 40

The product of two tables is also called the ____ product.

A)Cartesian
B)aggregate
C)Cathode
D)exponential

Question 41

____________________ is a theoretical way of manipulating a relational database.

Question 42

What is the difference between an AND criterion and an OR criterion? How is each criterion created in QBE?

Question 43

In Access,you can add all fields from a table to the design grid by double-clicking the ____________________ in the table's field list.

Question 44

Explain what relational algebra is and how it is used.

Question 45

To find the total of all customers' balances,use the ____________________ function.

Question 46

List at least six of the aggregate functions available in Access. Explain how to use any of these functions in a query.

Question 47

Discuss the difference between the major sort key and the minor sort key.

Question 48

To list the records in a query's results in a particular order,you need to ____________________ the records.

Question 49

Provide a definition for the term relation.

Question 50

In relational algebra,the ____________________ of two tables is table containing all rows that are common in both table A and table B.