Exam 3: The Relational Database Model

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

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

____ yields only the rows that appear in both tables.

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

Controlled ____ makes a relational database work.

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

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.

Describe the use of the UNION operator.

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

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

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

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

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

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.

Tables within a database share common attributes that enable the tables to be linked together.

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

DBMSs use indexes for many different purposes.

____________________ relationships can be implemented by creating a new entity in 1:M relationships with the original entities.

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

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