Exam 3: The Relational Database Model

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

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.

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

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

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

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

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.

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

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

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

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

The row's range of permissible values is known as its domain.

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

A is the primary key of one table that has been placed into another table to create a common attribute.

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