4620 Chapter 3
The _____ relationship should be rare in any relational database design. 1:1 1:M M:1 M:N
1:1
The _____ relationship is the "relational model ideal." 1:1 1:M M:1 M:N
1:M
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. entity referential relational null
entity
The _____ is actually a system-created database whose tables store the user/designer-created database characteristics and contents. database tuple systematic database unique index system catalog
system catalog
The SELECT operator yields a vertical subset of a table.
False
A _____ is the primary key of one table that has been placed into another table to create a common attribute. superkey composite primary key candidate key foreign key
foreign key
In a database context, the word _____ indicates the use of the same attribute name to label different attributes. redundancy homonym duplicate synonym
homonym
A(n) _____ is an orderly arrangement used to logically access rows in a table. primary rule superkey relationship index
index
A(n) _____ only returns matched records from the tables that are being joined.
inner join
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
Only a single attribute, not multiple attributes, can define functional dependence.
False
The idea of determination is unique to the database environment.
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
The row's range of permissible values is known as its domain.
False
Date attributes contain calendar dates stored in a special format known as the _____ date format. Epoch calendar Julian logical
Julian
_____ relationships can be implemented by creating a new entity in 1:M relationships with the original entities. 1:N M:1 M:N 1:1
M:N
The _____ constraint can be placed on a column to ensure that every row in the table has a value for that column UNIQUE NOT NULL VALUE EMPTY
NOT NULL
_____ returns only the attributes requested, in the order in which they are requested PROJECT SELECT UNION DIFFERENCE
PROJECT
_____ logic, used extensively in mathematics, provides a framework in which an assertion (statement of fact) can be verified as either true or false. Predicate Database Relational Index
Predicate
To be considered minimally relational, the DBMS must support the key relational operators _____, PROJECT, and JOIN. INTERSECT UNION DIFFERENCE SELECT
SELECT
_____, also known as RESTRICT, yields values for all rows found in a table that satisfy a given condition. INTERSECT UNION DIFFERENCE SELECT
SELECT
A data dictionary is sometimes described as "the database designer's database" because it records the design decisions about tables and their structures.
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
As rare as 1:1 relationships should be, certain conditions absolutely require their use.
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
RDBMSs enforce integrity rules automatically.
True
Relational algebra defines the theoretical way of manipulating table contents using relational operators.
True
The DIFFERENCE operator subtracts one table from the other.
True
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.
True
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.
True
You can think of a table as a persistent representation of a logical relation.
True
Another name for a composite entity is a(n) _____ entity. bridge linked directive associative
bridge
A _____ key can be described as a minimal superkey, a superkey without any unnecessary attributes. secondary candidate primary foreign
candidate
Each table _____ represents an attribute. column row dimension value
column
A _____ contains at least all of the attribute names and characteristics for each table in the system. data dictionary relational schema logical schema database
data dictionary
Referential _____ dictates that the foreign key must contain values that match the primary key in the related table, or must contain null. integrity uniqueness model attribute
integrity
In the relational model, _____ are important because they are used to ensure that each row in a table is uniquely identifiable. relations keys indexes logical structures
keys
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). distribution independence logical data independence comprehensive data sublanguage integrity independence
logical data independence
A(n) _____ join links tables by selecting only the rows with common values in their common attribute(s). attribute unique foreign natural
natural
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. nonsubversion information guaranteed access view updating
nonsubversion
_____ are especially useful when you are trying to determine what values in related tables cause referential integrity problems. Inner joins Outer joins Equijoins Theta joins
outer joins
A _____ key is defined as a key that is used strictly for data retrieval purposes. lookup foreign candidate secondary
secondary
A _____ is any key that uniquely identifies each row. superkey special key foreign key candidate key
superkey
In a database context, a(n) _____ indicates the use of different names to describe the same attribute. entity duplicate synonym homonym
synonym
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 _____. intersect-compatible union-compatible difference-compatible select-compatible
union-compatible
When you define a table's primary key, the DBMS automatically creates a(n) _____ index on the primary key column(s) you declared. key composite unique primary
unique
