Exam 3: The Relational Database Model

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

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

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

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

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).

Describe the use of nulls in a database.

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

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

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

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

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

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.

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

In a relational model,if A determines B,C,and D,you write A = B,C,D.

DBMSs use indexes for many different purposes.

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

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

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

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

What are the characteristics of a relational table?