• Question 18 Any attribute that is part of a key is known as a ____.
• Question 19 ____ combines all rows from two tables , excluding duplicate rows .
• Question 20 A ( n ) ____ is perceived as a two-dimensional structure composed of rows and columns .
• 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 Since it is used to link the tables that originally were related in a M : N relationship , the composite entity structure includes — as foreign keys — at least the ____ keys of the tables that are to be linked .
• Question 23 A ( n ) ____ join only returns matched records from the tables that are being joined .
• Question 24 In an outer join , the matched pairs would be retained and any unmatched values in the other table would be left ____.
• Question 25 A ____ identifier is composed of more than one attribute .
• 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 Another word for existence-independent is ____.
• Question 28 A ____ relationship exists when an association is maintained within a single entity .
• Question 29 Knowing the ____ number of entity occurrences is very helpful at the application software level .
• Question 30 A ____ relationship exists when three entities are associated .