Exam 3: The Relational Database Model

All primary key entries are unique,and no part of a primary key may be ____.

The proper use of ____________________ keys is crucial to controlling data redundancy.

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

The following example exhibits ____________________ integrity: The CUSTOMER table's primary key is CUS_CODE.The CUSTOMER primary key column has no null entries,and all entries are unique.Similarly,the AGENT table's primary key is AGENT_CODE,and this primary key column also is free of null entries.

____ yields only the rows that appear in both tables.

A proper understanding of the concept and use of keys in a relational database model is very important.

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

The logical view of the relational database is facilitated by the creation of data relationships based on a logical construct known as a(n)____________________.

If the attribute (B)is functionally dependent on a composite key (A)but not on any subset of that ____ key,the attribute (B)is fully functionally dependent on (A).

A null is created when you press the Enter key or the Tab key to move to the next entry without making a prior entry of any kind.

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

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

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

Fortunately,the problems inherent in the ____________________ relationship can easily be avoided by creating a composite entity.

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

A left outer join on tables CUSTOMER and AGENT yields all of the rows in the CUSTOMER table,including those that do not have a matching value in the AGENT table

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.

____________________ joins are especially useful when you are trying to determine what value(s)in related tables cause(s)referential integrity problems.

The DIFFERENCE operator subtracts one table from the other.

A(n)____ is an ordered arrangement of keys and pointers.