Entity Relationships - Quiz Explanation

The answers you selected are indicated below, along with text that explains the correct answers.
 
1. What type of relationship is described by the following rule? For one instance of entity A, there exists zero, one, or many instances of entity B; and for one instance of entity B, there exists zero, one, or many instances of entity A.
Please select the best answer.
  A. 1:1 relationship
  B. 1:N relationsip
  C. M:N relationship
  The correct answer is C. An M:N relationship exists when, for one instance of entity A, there exists zero, one, or many instances of entity B; and for one instance of entity B, there exists zero, one, or many instances of entity A. Answer A is incorrect because a 1:1 relationship exists when zero or one instance of entity A can be associated with zero or one instance of entity B, and zero or one instance of entity B can be associated with zero or one instance of entity A. Answer B is incorrect because a 1:N relationship exists when, for one instance of entity A, there exists zero, one, or many instances of entity B; but for one instance of entity B, there exists zero or one instance of entity A.

2. What type of relationship is described by this rule? For one instance of entity A, there exists zero, one, or many instances of entity B; but for one instance of entity B, there exists zero or one instance of entity A.
Please select the best answer.
  A. 1:1 relationship
  B. 1:N relationship
  C. M:N relationship
  The correct answer is B. A 1:N relationship exists when, for one instance of entity A, there exists zero, one, or many instances of entity B; but for one instance of entity B, there exists zero or one instance of entity A. Answer A is incorrect because a 1:1 relationship exists when zero or one instance of entity A can be associated with zero or one instance of entity B, and zero or oneinstance of entity B can be associated with zero or one instance of entity A. Answer C is incorrect because a M:N relationship exists when, for one instance of entity A, there exists zero, one, or many instances of entity B; and for one instance of entity B, there exists zero, one, or many instances of entity A.

3. What type of relationship is described by this rule? Zero or one instance of entity A can be associated with zero or one instance of entity B, and zero or one instance of entity B can be associated with zero or one instance of entity A.
Please select the best answer.
  A. 1:1 relationship
  B. 1:N relationship
  C. M:N relationship
  The correct answer is A. A 1:1 relationship exists when zero or one instance of entity A can be associated with zero or one instance of entity B, and zero or one instance of entity B can be associated with zero or one instance of entity A. Answer B is incorrect because a 1:N relationship exists when, for one instance of entity A, there exists zero, one, or many instances of entity B; but for one instance of entity B, there exists zero or one instance of entity A. Answer C is incorrect because a M:N relationship exists when, for one instance of entity A, there exists zero, one, or many instances of entity B; and for one instance of entity B, there exists zero, one, or many instances of entity A.

4. What type of participation does the following sentence describe for Table A? There is no requirement for any records to exist in Table A before any records can be added to Table B.
Please select the best answer.
  A. Mandatory participation
  B. Optional participation
  C. None of the above
  The correct answer is B. Table A has optional participation because there is no requirement for any records to exist in it before any records can be added to Table B.
Answer A is incorrect because mandatory participation requires that one record must exist in Table A before any records can be added to Table B.

5. What type of participation is described for Table B? One record must exist in Table B before any records can be added to Table A.
Please select the best answer.
  A. Mandatory participation
  B. Optional participation
  C. None of the above
  The correct answer is A. Table B has mandatory participation because it must contain one record before any records can be added to Table A. Answer B is incorrect because optional participation has no requirement for any records to exist in Table B before any records can be added to Table A.

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