IT 214 - Quiz 2

A(n) ____ is perceived as a two-dimensional structure composed of rows and columns.

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

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

The relational model's creator, E. F. Codd, used the term relation as a synonym for ____.

Attribute A determines attribute B (that is, B is functionally ____________________ on A) if all of the rows in the table that agree in value for attribute A also agree in value for attribute B.

In the context of a database table, the statement "A ____ B" indicates that if you know the value of attribute A, you can look up the value of attribute B.

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

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

In the following table description, ____ is the primary key. PRODUCT (PROD_CODE, PROD_DESCRIPT, PROD_PRICE, PROD_ON_HAND, VEND_CODE)

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

Numeric data are data on which you can perform meaningful arithmetic procedures.

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

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

____ logic, used extensively in mathematics, provides a framework in which an assertion (statement of fact) can be verified as either true or false.

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

A(n) ____________________ key can be described as a superkey without unnecessary attributes.

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

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.

____ yields a vertical subset of a table.

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

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

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

Proper data ____________________ design requires carefully defined and controlled data redundancies to function properly.

A CUSTOMER table's primary key is CUS_CODE. The CUSTOMER primary key column has no null entries, and all entries are unique. This is an example of ____ integrity.

There is never a good reason to use null values in a database.

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

A(n) ____________________ is an orderly arrangement used to logically access rows in a table.

In an outer join, the matched pairs would be retained and any unmatched values in the other table would be left ____.

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

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

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

In a natural join, the column on which the join was made occurs twice in the new table.

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

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.

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

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

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

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

The SELECT operator yields a vertical subset of a table.

The relational database model enables you to view data ____ rather than ____.

The equijoin takes its name from the comparison operator ____ used in the condition.

A ____ key can be described as a superkey without unnecessary attributes, that is, a minimal superkey.

Depending on the sophistication of the application development software, nulls can create problems when functions such as COUNT, AVERAGE, and SUM are used.

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.

A ____ is a textual representation of the database tables where each table is listed by its name followed by the list of its attributes in parentheses.

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.

____ yields only the rows that appear in both tables.

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.

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.

Current relational database software generally provides only a system catalog (and not a data dictionary).

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

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

A foreign key must exist in both tables that have a relationship.

Controlled ____ makes a relational database work.

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

The ____________________ relationship is the relational database norm.

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

A ____ contains at least all of the attribute names and characteristics for each table in the system.

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

The DIFFERENCE operator subtracts one table from the other.

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

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

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).

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

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

Tables must have the same attribute characteristics (the columns and domains must be compatible) to be used in a UNION.

A ____ is any key that uniquely identifies each row.