Database_CH3_Quiz

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

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

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

RDBMSs enforce integrity rules automatically.

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

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

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.

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

The SELECT operator yields a vertical subset of a table.

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.

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

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

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

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

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

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

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

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

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

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

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

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

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 _____ is any key that uniquely identifies each row.

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

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

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

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

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

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

Each table _____ represents an attribute.

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

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

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

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

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.

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

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

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.

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

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

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

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

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

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

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

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

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

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