Exam 3: The Relational Database Model

The DIFFERENCE operator subtracts one table from the other.

A is any key that uniquely identifies each row.

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 .

According to Codd's rule of relational database, "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 key can be described as a minimal superkey, a superkey without any unnecessary attributes.

Each table represents an attribute.

The relationship is the relational database norm.

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

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.

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

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

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

relationships cannot be implemented as such in the relational model.

The idea of determination is unique to the database environment.

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

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

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

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

A table is also called a(n) because the relational model's creator, E. F. Codd, used the two terms as synonyms.

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