• Question 18 Referential ____ means that if the foreign key contains a value , that value refers to an existing valid tuple ( row ) in another relation .
• Question 19 All primary key entries are unique , and no part of a primary key may be ____.
• Question 20 A ____ contains at least all of the attribute names and characteristics for each table in the system .
• Question 21 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 .
• Question 22 A ( n ) ____ is an ordered arrangement of keys and pointers .
• 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 ____ combines all rows from two tables , excluding duplicate rows .
• Question 25 Another word for existence-independent is ____.
• Question 26 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 27 A derived attribute ____.
• Question 28 Knowing the ____ number of entity occurrences is very helpful at the application software level .
• Question 29 A ____ relationship exists when three entities are associated .
• Question 30 If an entity can exist apart from one or more related entities , it is said to be ____ -independent .
• Question 31 A ____ should be a derived attribute .