University:
California State University, Northridge
Course:
COMP 440 | Database Design
Academic year:

2024
Views:

367

Pages:

15
Author:

Samuel K.

Quiz: Entity Relationship (ER) Modeling A+ Due Sep 27 at 11:59pm Points 15 Questions 15 Time Limit 30 Minutes Allowed Attempts 2 Take the Quiz Again Attempt History Attempt Time Score LATEST Attempt 1 20 minutes 14 out of 1.5 Question 1 1/1 pts If the entity COURSE is related to the entity CLASS, then it is only necessary to determine the connectivity of the relationship from COURSE to CLASS. True False Correct. COURSE or CLASS can also relate to other entities such as "PROFESSOR teaches CLASS." Question 2 1/1 pts In Chen notation, there is no way to represent cardinality. True False Correct. The Chen notation places the cardinalities on the side of the related entity. Question 11 1/1 pts In a M:N relationship between STUDENT and CLASS at a university, it is possible that a class may start with no students and a student may start with no classes. If a database designer is using the O symbol using the Chen model, what is the designer hoping to establish between these entities? A cardinality figure. An optional relationship. Correct. STUDENT and CLASS do not require each other to exist, but they can be related once a student is assigned a class, eventually. The relationship is optional. A set of optional identifiers. A domain of possible values. Question 12 Not yet graded / 1 pts Explain recursive relationships with the help of an example. Your Answer: Recursive relationships occur when an entity is related to itself. For example, EMPLOYEE entity. An employee such as a manager, can supervise other employees. In this case, the relationship is recursive because an employee is related to other employees within the same entity. Question 13 1/1 pts When a database designer determines that two entities share the same primary keys in their relationship, what can the designer infer between the two? Unary relationship optional relationship strong relationship Correct. Strong relationship because a strong (identifying) relationship exists when the primary key of the related entity contains a primary key component of the parent entity. weak relationship Question 14 1/1 pts In some cases where an association is maintained within a single entity, a database designer should depict with a line on itself. If a manager is able to manage other employees. how would the EMPLOYEE table's relationship degree be described as? ternary higher-order binary unary Correct. Unary because a unary relationship exists when an association is maintained within a single entity. Question 15 1/1 pts A database designer set the CRS_CODE attribute as the primary key to the CLASS table. If no other changes are made, how many composite identifiers does the table have? Three One Zero Correct. A composite identifier is a primary key composed of more than one attribute. Two