Deck 3: The Relational Database Model

Question 1

The SELECT operator yields a vertical subset of a table.

Answer 1

False

Question 2

The DIVIDE operation uses one single­column table (e.g.,column "a")as the divisor and one two­column table (e.g.,columns "a" and "b")as the dividend.

Answer 2

True

Question 3

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.

Answer 3

True

Question 4

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

Question 5

RDBMSs enforce integrity rules automatically.

Question 6

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

Question 7

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 8

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

Question 9

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

Question 10

The idea of determination is unique to the database environment.

Question 11

The one­to­many (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 12

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

Question 13

The DIFFERENCE operator subtracts one table from the other.

Question 14

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

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

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

Question 17

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

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

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

Question 20

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

Question 21

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 22

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

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

Question 23

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

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

Question 24

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 25

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 26

Each table represents an attribute.

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

Question 27

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 28

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 29

A is any key that uniquely identifies each row.

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

Question 30

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 31

__ ,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 32

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 33

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 34

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 35

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

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

Question 36

_ are especially useful when you are trying to determine what values in related tables cause referential integrity problems.
a.Inner joins
b.Outer joins
b.Theta joins
d.Equijoins

Question 37

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

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

Question 38

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 39

__ 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 40

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 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

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 43

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

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

Question 44

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

Question 45

The relationship should be rare in any relational database design.

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

Question 46

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

Question 47

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

Question 48

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

Question 49

The relationship is the "relational model ideal."

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

Question 50

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

Question 51

According to Codd's rule of relational database,"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)nonsubversion
B)logical data independence
C)comprehensive data sublanguage
D)integrity independence

Question 52

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

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

Question 53

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 54

_____ 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 55

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

Question 56

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

Question 57

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

Question 58

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 59

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

Question 60

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

Question 61

Describe the use of null values in a database.

Question 62

______relationships cannot be implemented as such in the relational model.

Question 63

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

Question 64

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

Question 65

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

Question 66

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 67

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

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

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

Question 70

The relationship is the relational database norm.

Question 71

Describe the use of the INTERSECT operator.

Question 72

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

Question 73

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

Question 74

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