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Intro to Database Systems > Chapter 3 > Flashcards

Chapter 3 Flashcards

1
Q

The practical significance of taking the logical view of a database is that it serves as a reminder of the simple file concept of data storage.

A

True

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2
Q

Because the relational model uses attribute values to establish relationships among tables, many database users correctly assume that the term relation refers to such relationships.

A

False

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3
Q

Numeric data are data on which you can perform meaningful arithmetic procedures.

A

True

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4
Q

Each table in a relational database must have a primary key.

A

True

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5
Q

In a relational model, if A determines B, C, and D, you write A = B, C, D.

A

False

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6
Q

If the attribute (B) is functionally dependent on a composite key (A) but not on any subset of that composite key, the attribute (B) is fully functionally dependent on (A).

A

True

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7
Q

There is never a good reason to use null values in a database.

A

False

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8
Q

Tables within a database share common attributes that enable the tables to be linked together.

A

True

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9
Q

RDBMSs enforce integrity rules automatically.

A

True

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10
Q

The SELECT operator yields a vertical subset of a table.

A

False

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11
Q

The DIFFERENCE operator subtracts one table from the other.

A

True

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12
Q

A left outer join on tables CUSTOMER and AGENT yields all of the rows in the CUSTOMER table, including those that do not have a matching value in the AGENT table.

A

True

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13
Q

Which of the following is used to select partial table contents?

A

SELECT
FROM
BY ;

LIST
FROM
BY ;

-SELECT
FROM
WHERE ;

LIST
FROM
WHERE ;

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14
Q

Which query will output the table contents when the value of V_CODE is not equal to 21344?

A

-SELECT P_DESCRIPT, P_INDATE, P_PRICE, V_CODE
FROM PRODUCT
WHERE V_CODE <> 21344;

SELECT P_DESCRIPT, P_INDATE, P_PRICE, V_CODE
FROM PRODUCT
WHERE V_CODE <= 21344;

SELECT P_DESCRIPT, P_INDATE, P_PRICE, V_CODE
FROM PRODUCT
WHERE V_CODE = 21344;

SELECT P_DESCRIPT, P_INDATE, P_PRICE, V_CODE
FROM PRODUCT
WHERE V_CODE => 21344;

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15
Q

Which query will output the table contents when the value of the character field P_CODE is alphabetically less than 1558-QW1?

A

-SELECT P_CODE, P_DESCRIPT, P_QOH, P_MIN, P_PRICE
FROM PRODUCT
WHERE P_CODE

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16
Q

You can think of a table as a persistent representation of a logical relation.

A

True

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17
Q

The order of the rows and columns is important to the DBMS.

A

False

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18
Q

Character data can contain any character or symbol intended for mathematical manipulation.

A

False

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19
Q

The idea of determination is unique to the database environment.

A

False

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20
Q

Only a single attribute, not multiple attributes, can define functional dependence.

A

False

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21
Q

A null is created when you press the Enter key or the Tab key to move to the next entry without making a prior entry of any kind.

A

True

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22
Q

Depending on the sophistication of the application development software, nulls can create problems when functions such as COUNT, AVERAGE, and SUM are used.

A

True

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23
Q

A foreign key must exist in both tables that have a relationship.

A

False

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24
Q

Referential and entity integrity are two names for the same thing.

A

False

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25
Q

Tables must have the same attribute characteristics (the columns and domains must be compatible) to be used in a UNION.

A

True

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26
Q

The DIFFERENCE operator subtracts one table from the other.

A

True

27
Q

In a natural join, the column on which the join was made occurs twice in the new table.

A

False

28
Q

The DIVIDE operation uses one single-column table (e.g., column “a”) as the divisor and one two-column table (e.g., columns “a” and “b”) as the dividend.

A

True

29
Q

A data dictionary contains metadata—data about data.

A

True

30
Q

A data dictionary is sometimes described as “the database designer’s database” because it records the design decisions about tables and their structures.

A

True

31
Q

The one-to-many (1:M) relationship is easily implemented in the relational model by putting the foreign key of the “1” side in the table of the “many” side as a primary key.

A

False

32
Q

As rare as 1:1 relationships should be, certain conditions absolutely require their use.

A

True

33
Q

DBMSs use indexes for many different purposes.

A

True

34
Q

____ logic, used extensively in mathematics, provides a framework in which an assertion (statement of fact) can be verified as either true or false.

A

Predicate

35
Q

The relational database model enables you to view data ____ rather than ____.

A

Logically, physically

36
Q

A(n) ____ is perceived as a two-dimensional structure composed of rows and columns.

A

Table

37
Q

Date attributes contain calendar dates stored in a special format known as the ____ date format.

A

Julian

38
Q

____ data can have only a true or false (yes or no) values.

A

Logical

39
Q

In the context of a database table, the statement “A ____ B” indicates that if you know the value of attribute A, you can look up the value of attribute B.

A

determines

40
Q

The attribute B is ____ the attribute A if each value in column A determines one and only one value in column B.

A

functionally dependent on

41
Q

Any attribute that is part of a key is known as a ____.

A

key attribute

42
Q

No data entry at all is known as a(n) ____.

A

null

43
Q

Controlled ____ makes a relational database work.

A

redundancy

44
Q

Referential ____ means that if the foreign key contains a value, that value refers to an existing valid tuple (row) in another relation.

A

integrity

45
Q

A ____ key can be described as a superkey without unnecessary attributes, that is, a minimal superkey.

A

candidate

46
Q

All primary key entries are unique, and no part of a primary key may be ____.

A

null

47
Q

A CUSTOMER table’s primary key is CUS_CODE. The CUSTOMER primary key column has no null entries, and all entries are unique. This is an example of ____ integrity.

A

entity

48
Q

To be considered minimally relational, the DBMS must support the key relational operators ____, PROJECT, and JOIN.

A

SELECT

49
Q

____, also known as RESTRICT, yields values for all rows found in a table that satisfy a given condition.

A

SELECT

50
Q

____ yields a vertical subset of a table.

A

PROJECT

51
Q

____ yields only the rows that appear in both tables.

A

INTERSECT

52
Q

A(n) ____ join links tables by selecting only the rows with common values in their common attribute(s).

A

natural

53
Q

The equijoin takes its name from the comparison operator ____ used in the condition.

A

=

54
Q

A(n) ____ join only returns matched records from the tables that are being joined.

A

inner

55
Q

A ____ contains at least all of the attribute names and characteristics for each table in the system.

A

data dictionary

56
Q

The ____ is actually a system-created database whose tables store the user/designer-created database characteristics and contents.

A

system catalog

57
Q

In a database context, a(n) ____ indicates the use of different names to describe the same attribute.

A

synonym

58
Q

The ____ relational type is the “relational model ideal.”

A

1:M

59
Q

The ____ relationship should be rare in any relational database design.

A

1:1

60
Q

Another name for a composite entity is a ____ entity.

A

bridge

61
Q

A(n) ____ is an ordered arrangement of keys and pointers.

A

index

62
Q

When you define a table’s primary key, the DBMS automatically creates a(n) ____ index on the primary key column(s) you declared.

A

unique

63
Q

Codd’s Rule of ____ states:
If the system supports low-level access to the data, users must not be allowed to bypass the integrity rules of the database

A

Nonsubversion

Intro to Database Systems (11 decks)

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