• Question 18 All primary key entries are unique , and no part of a primary key may be ____.
• Question 19 ____ yields only the rows that appear in both tables .
• Question 20 ____ combines all rows from two tables , excluding duplicate rows .
• Question 21 The ____ relationship should be rare in any relational database design .
• Question 22 A ( n ) ____ join only returns matched records from the tables that are being joined .
• Question 23 In an outer join , the matched pairs would be retained and any unmatched values in the other table would be left ____.
• Question 24 A ( n ) ____ is perceived as a two-dimensional structure composed of rows and columns .
• Question 25 A ____ should be a derived attribute .
• Question 26 A relationship is an association between ____.
• Question 27 Ideally , an entity identifier is composed of ____ attribute ( s ).
• Question 28 An entity is said to be ____ -dependent if it can exist in the database only when it is associated with another related entity occurrence .
• Question 29 A derived attribute ____.
• Question 30 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 31 Knowing the ____ number of entity occurrences is very helpful at the application software level .