Ch 3 and 5

If one department chair—a professor—can chair only one department and one department can have only one department chair, then the entities PROFESSOR and DEPARTMENT exhibit a(n) ____________________ relationship.

1:1

The ____________________ relationship is the relational database norm.

1:M

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

=

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

Cartesian

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

Join

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

NOT NULL

In the following table description, ____ is the primary key. PRODUCT (PROD_CODE, PROD_DESCRIPT, PROD_PRICE, PROD_ON_HAND, VEND_CODE)

PROD_CODE

____ yields a vertical subset of a table.

Project

If the foreign key contains either matching values or nulls, the table that makes use of that foreign key is said to exhibit ____________________ integrity

Referential

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

SELECT

The relational model's creator, E. F. Codd, used the term relation as a synonym for ____.

Table

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

candidate

A(n) ____________________ key can be described as a superkey without unnecessary attributes.

candidate

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

data dictionary

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

data dictionary

Attribute A determines attribute B (that is, B is functionally ____________________ on A) if all of the rows in the table that agree in value for attribute A also agree in value for attribute B.

dependent

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.

determines

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.

entity

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

false

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.

false

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

false

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

false

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

false

The SELECT operator yields a vertical subset of a table.

false

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.

false

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

false

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

false

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

foreign

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

functionally dependent on

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

homonym

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

index

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

index

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

integrity

____ yields only the rows that appear in both tables.

intersect

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

keys

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

logical

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

logically, physically

Fortunately, the problems inherent in the ____________________ relationship can easily be avoided by creating a composite entity.

many-to-many (M:N)

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

natural

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

null

In an outer join, the matched pairs would be retained and any unmatched values in the other table would be left ____.

null

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

null

____________________ joins are especially useful when you are trying to determine what value(s) in related tables cause(s) referential integrity problems.

outer

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

predicate

Controlled ____ makes a relational database work.

redundency

The logical view of the relational database is facilitated by the creation of data relationships based on a logical construct known as a(n) ____________________.

relation

A ____ is a textual representation of the database tables where each table is listed by its name followed by the list of its attributes in parentheses.

relational schema

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

secondary

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

select

A ____ is any key that uniquely identifies each row.

superkey

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

synonym

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

system catalog

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

table

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

true

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.

true

A proper understanding of the concept and use of keys in a relational database model is very important.

true

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

true

Current relational database software generally provides only a system catalog (and not a data dictionary).

true

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

true

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

true

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).

true

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

true

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

true

The DIFFERENCE operator subtracts one table from the other.

true

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

true

____ combines all rows from two tables, excluding duplicate rows.

union

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

unique

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

unique

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

warehousing