• Question 18 A ( n ) ____ is an ordered arrangement of keys and pointers .
• Question 19 ____ combines all rows from two tables , excluding duplicate rows .
• Question 20 In the relational model , ____ are important because they are used to ensure that each row in a table is uniquely identifiable .
• Question 21 A ____ is any key that uniquely identifies each row .
• Question 22 The ____ constraint can be placed on a column to ensure that every row in the table has a value for that column .
• Question 23 A ____ contains at least all of the attribute names and characteristics for each table in the system .
• Question 24 ____ yields only the rows that appear in both tables .
• Question 25 The M : N relationship between STUDENT and CLASS must be divided into two 1 : M relationships through the use of the ENROLL entity ; the ENROLL entity is ____.
• Question 26 A relationship is an association between ____.
• Question 27 A ____ relationship exists when an association is maintained within a single entity .
• Question 28 A ____ entity has a primary key that is partially or totally derived from the parent entity in the relationship .
• Question 29 ____ relationships are most common .
• Question 30 A ____ identifier is composed of more than one attribute .
• Question 31 An entity is said to be ____ -dependent if it can exist in the database only when it is associated with another related entity occurrence .