1Z0-006 Entity-Relationship Modeling 3 — Questions and Answers
Question 1: An entity that cannot be uniquely identified by its own attributes alone and depends on another entity is called a:
- Strong entity
- Weak entity (Correct answer)
- Associative entity
- Derived entity
Correct answer: Weak entity
A weak entity lacks sufficient attributes to form its own primary key and relies on its owner (strong) entity for full identification.
Question 2: In ER modeling, 'participation constraint' refers to:
- The maximum number of relationships an entity can have
- Whether every entity instance must participate in a relationship (total) or participation is optional (partial) (Correct answer)
- The data type assigned to a relationship attribute
- The rule that prevents duplicate entity names
Correct answer: Whether every entity instance must participate in a relationship (total) or participation is optional (partial)
Participation constraints specify whether all (total) or only some (partial) entity instances must participate in a given relationship.
Question 3: What does a '1' on one side and an 'M' on the other side of a relationship line signify?
- Many-to-many relationship
- One-to-one relationship
- One-to-many relationship (Correct answer)
- Mandatory participation on both sides
Correct answer: One-to-many relationship
A 1:M (one-to-many) relationship means one instance on the '1' side can be associated with multiple instances on the 'M' side.
Question 4: Which of the following is TRUE about a recursive (unary) relationship?
- It involves exactly two different entity types
- It is a relationship where an entity type is associated with itself (Correct answer)
- It can only have a 1:1 cardinality
- It cannot be represented in a relational schema
Correct answer: It is a relationship where an entity type is associated with itself
A unary (recursive) relationship associates instances of a single entity type with each other, such as an Employee who manages other Employees.
Question 5: When an ER diagram shows a relationship with an attribute (e.g., 'Date' on a WORKS_FOR relationship), what does this indicate?
- The attribute belongs to one of the participating entities
- The attribute describes a property of the relationship itself, not either entity alone (Correct answer)
- The attribute is a primary key of a new entity
- The attribute is derived and should not be stored
Correct answer: The attribute describes a property of the relationship itself, not either entity alone
Relationship attributes capture information that only makes sense in the context of the association between two entities, not either entity individually.
Question 6: In the Chen ER notation, a diamond shape represents:
- An entity type
- An attribute
- A relationship type (Correct answer)
- A primary key attribute
Correct answer: A relationship type
In Chen notation, diamond shapes denote relationship types connecting two or more entity types.
Question 7: Which type of attribute is depicted with a dashed underline in an ER diagram?
- Primary key attribute
- Multivalued attribute
- Discriminator (partial key) of a weak entity (Correct answer)
- Derived attribute
Correct answer: Discriminator (partial key) of a weak entity
A dashed underline marks the discriminator (partial key) of a weak entity, distinguishing it from a full primary key marked with a solid underline.
1Z0-006 Entity-Relationship Modeling 3
An entity that cannot be uniquely identified by its own attributes alone and depends on another entity is called a: