Deck 3: The Relational Database Model

Question 1

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

Answer 1

False

Question 2

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

Answer 2

True

Question 3

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.

Answer 3

True

Question 4

The SELECT operator yields a vertical subset of a table.

Question 5

The row's range of permissible values is known as its domain.

Question 6

The idea of determination is unique to the database environment.

Question 7

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

Question 8

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

Question 9

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

Question 10

RDBMSs enforce integrity rules automatically.

Question 11

Relational algebra defines the theoretical way of manipulating table contents using relational operators.

Question 12

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

Question 13

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.

Question 14

The DIFFERENCE operator subtracts one table from the other.

Question 15

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

Question 16

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).

Question 17

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

Question 18

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.

Question 19

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.

Question 20

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

Question 21

_____ are especially useful when you are trying to determine what values in related tables cause referential integrity problems.

A) Inner joins
B) Outer joins
C) Equijoins
D) Theta joins

Question 22

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

A) INTERSECT
B) UNION
C) DIFFERENCE
D) SELECT

Question 23

When two or more tables share the same number of columns, and when their corresponding columns share the same or compatible domains, they are said to be _____.

A) intersect-compatible
B) union-compatible
C) difference-compatible
D) select-compatible

Question 24

In the relational model, _____ are important because they are used to ensure that each row in a table is uniquely identifiable.

A) relations
B) keys
C) indexes
D) logical structures

Question 25

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

A) Epoch
B) calendar
C) Julian
D) logical

Question 26

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

A) attribute
B) unique
C) foreign
D) natural

Question 27

A _____ is the primary key of one table that has been placed into another table to create a common attribute.

A) superkey
B) composite primary key
C) candidate key
D) foreign key

Question 28

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

A) data dictionary
B) relational schema
C) logical schema
D) database

Question 29

The 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
B) referential
C) relational
D) null

Question 30

_____ 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
B) Database
C) Relational
D) Index

Question 31

A _____ is any key that uniquely identifies each row.

A) superkey
B) special key
C) foreign key
D) candidate key

Question 32

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

A) outer join
B) inner join
C) equijoin
D) theta join

Question 33

_____ returns only the attributes requested, in the order in which they are requested.

A) PROJECT
B) SELECT
C) UNION
D) DIFFERENCE

Question 34

A _____ key is defined as a key that is used strictly for data retrieval purposes.

A) lookup
B) foreign
C) candidate
D) secondary

Question 35

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

A) INTERSECT
B) UNION
C) DIFFERENCE
D) SELECT

Question 36

Referential _____ dictates that the foreign key must contain values that match the primary key in the related table, or must contain null.

A) integrity
B) uniqueness
C) model
D) attribute

Question 37

The _____ constraint can be placed on a column to ensure that every row in the table has a value for that column.

A) UNIQUE
B) NOT NULL
C) VALUE
D) EMPTY

Question 38

Each table _____ represents an attribute.

A) column
B) row
C) dimension
D) value

Question 39

A _____ key can be described as a minimal superkey, a superkey without any unnecessary attributes.

A) secondary
B) candidate
C) primary
D) foreign

Question 40

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

A) database tuple
B) systematic database
C) unique index
D) system catalog

Question 41

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

A) key
B) composite
C) unique
D) primary

Question 42

According to Codd's _____ rule of relational databases, application programs and ad hoc facilities are logically unaffected when changes are made to the table structures that preserve the original table values (changing order of columns or inserting columns).

A) distribution independence
B) logical data independence
C) comprehensive data sublanguage
D) integrity independence

Question 43

A(n) _____ links tables on the basis of an equality condition that compares specified columns of each table.

Question 44

In a database context, the word _____ indicates the use of the same attribute name to label different attributes.

A) redundancy
B) homonym
C) duplicate
D) synonym

Question 45

The _____ relationship is the "relational model ideal."

A) 1:1
B) 1:M
C) M:1
D) M:N

Question 46

_____ relationships can be implemented by creating a new entity in 1:M relationships with the original entities.

A) 1:N
B) M:1
C) M:N
D) 1:1

Question 47

In a relational table, each column has a specific range of values known as the _____ domain.

Question 48

_____ is the real power behind the relational database, allowing the use of independent tables linked by common attributes.

Question 49

A table is also called a(n) _____ because the relational model's creator, E. F. Codd, used the two terms as synonyms.

Question 50

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

A) entity
B) duplicate
C) synonym
D) homonym

Question 51

A(n) _____ is an orderly arrangement used to logically access rows in a table.

A) primary rule
B) superkey
C) relationship
D) index

Question 52

To avoid nulls, some designers use special codes, known as _____, to indicate the absence of some value.

Question 53

The relational operators have the property of _____; that is, the use of relational algebra operators on existing relations (tables) produces new relations.

Question 54

PRODUCT yields all possible pairs of rows from two tables, also known as the _____ product.

Question 55

A(n) ______ provides a detailed description of all tables found within the user/designer-created database.

Question 56

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

A) 1:1
B) 1:M
C) M:1
D) M:N

Question 57

According to Codd's _____ rule of relational databases, 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
B) information
C) guaranteed access
D) view updating

Question 58

In a relational model, _____ are used to establish relationships among tables and to ensure the integrity of the data.

Question 59

Another name for a composite entity is a(n) _____ entity.

A) bridge
B) linked
C) directive
D) associative

Question 60

A primary key is a(n) _____ key chosen to be the primary means by which rows of a table are uniquely identified.

Question 61

An index key can have multiple _____ (a composite index).

Question 62

The _____ relationship is the relational database norm.

Question 63

The _____ catalog can be described as a detailed system data dictionary that describes all objects within the database, including data about table names, the table's creator and creation date, the number of columns in each table, the data type corresponding to each column, index filenames, index creators, authorized users, and access privileges.

Question 64

The proper use of _____ keys is crucial to controlling data redundancy.

Question 65

Describe the use of null values in a database.

Question 66

Describe the use of the INTERSECT operator.

Question 67

A(n) _____ index is an index in which the index key can have only one pointer value (row) associated with it.

Question 68

Dr. Codd's _____ rule of relational database states that every value in a table is guaranteed to be accessible through a combination of table name, primary key value, and column name.

Question 69

What is a key and how is it important in a relational model?

Question 70

If one department chair-a professor-can chair only one department, and one department can have only one department chair. The entities PROFESSOR and DEPARTMENT exhibit a(n) _____ relationship.

Question 71

_____ relationships cannot be implemented as such in the relational model.

Question 72

One characteristic of generalization hierarchies is that they are implemented as _____ relationships.

Question 73

Define entity integrity. What are the two requirements to ensure entity integrity?

Question 74

Define an index. Explain the role of indexes in a relational database.

Question 75

Proper data _____ design requires carefully defined and controlled data redundancies to function properly.