Q&A Hero

Design

Q: A hash mark across the relationship line near an entity indicates ________. A) a maximum cardinality of "zero" B) a maximum cardinality of "one" C) a minimum cardinality of "optional" D) a minimum cardinality of "required"
Q: In a minimum cardinality, minimums are generally stated as ________. A) 0 or 1 B) 1 or N C) M or N D) one or many
Q: Minimum cardinality refers to ________. A) the most instances of one entity class that can be involved in a relationship with one instance of another entity class B) the minimum number of entity classes involved in a relationship C) whether or not an instance of one entity class is required to be related to an instance of another entity class D) whether or not an entity is a weak entity
Q: You are given an E-R diagram with two entities, ORDER and CUSTOMER, as shown above, and are asked to draw the relationship between them. If a given customer can place many orders and a given order can be placed by one or more customers, which of the following should be indicated in the relationship symbol between the two entities? A) N:M B) 1:1 C) 1:N D) N:1
Q: You are given an E-R diagram with two entities, ORDER and CUSTOMER, as shown above, and are asked to draw the relationship between them. If a given customer can place many orders and a given order can be placed by at most one customer, which of the following should be indicated in the relationship symbol between the two entities? A) N:M B) 1:1 C) 1:N D) N:1
Q: You are given an E-R diagram with two entities, ORDER and CUSTOMER, as shown above, and are asked to draw the relationship between them. If a given customer can place only one order and a given order can be placed by at most one customer, which of the following should be indicated in the relationship symbol between the two entities?A) N:MB) 1:1C) 1:ND) N:1
Q: Maximum cardinality refers to ________.A) the most instances of one entity class that can be involved in a relationship instance with another entity classB) the minimum number of entity classes involved in a relationshipC) whether or not an instance of one entity class is required to be related to an instance of another entity classD) whether or not an entity is a weak entity
Q: Which of the following is not a common variant of the E-R model? A) IE Crow's Foot B) IDEF1X C) UML D) Object-oriented
Q: For a relationship to be considered a binary relationship it must satisfy which of the following conditions? A) It must involve exactly two entity classes. B) It must have a maximum cardinality of 1:1. C) It must have a maximum cardinality of 1:N. D) Both A and B are correct
Q: A composite attribute is an attribute that ________. A) is multivalued B) describes a characteristic of the relationship C) consists of a group of attributes D) is calculated at run-time
Q: An identifier may be ________. A) composite B) optional C) a relationship D) minimal
Q: Attributes may be ________. A) complete B) optional C) multivalued D) required
Q: The characteristics of a thing are described by its ________. A) identifiers B) entities C) objects D) attributes
Q: An occurrence of a particular entity is called an ________. A) entity class B) entity relationship C) entity instance D) entity attribute
Q: Entities of a given type are grouped into an ________. A) entity class B) entity relationship C) entity instance D) entity attribute
Q: Which of the following is not a key element of an E-R model? A) Relationships B) Entities C) Objects D) Attributes
Q: Which of the following is not a good reason for designing a data model? A) It's easier to change things in the data model than it is in the actual DBMS. B) The data model provides a simplified view of the database that can be shown to people who don't need to see all the details. C) Creating a data model will help you understand the application area better. D) The data model can be discarded after the database is operational.
Q: Recursive relationships only exist for one-to-one relationships.
Q: There are three types of recursive relationships: 1:1, 1:N, and N:M.
Q: Relationships among instances of a single entity class are called redundant relationships.
Q: Relationships between supertypes and subtypes are called IS-A relationships.
Q: Subtypes can be exclusive or inclusive.
Q: The supremetype entity contains the attributes that are common to all subtypes.
Q: Entities containing multivalued attributes are often represented using subtypes.
Q: Data modelers agree that weak, non-ID-dependent entities exist and are important.
Q: One example of a database design using an ID-dependent relationship is the archetype/instance pattern.
Q: One example of a database design using a strong relationship is the multivalued attribute pattern.
Q: One example of a database design using an ID-dependent relationship is the association pattern.
Q: Entities with an IS-A relationship should have the same identifier.
Q: An exclusive subtype pattern has one supertype entity that relates to one or more subtype entities.
Q: An attribute that determines which subtype is appropriate is called a discriminator.
Q: Subtype entities contain, apart from the identifier, only attributes that do not appear in the supertype.
Q: All weak entities must have a minimum cardinality of 1 on the entity on which it depends.
Q: ID-dependent entities are a common type of weak entity.
Q: A weak entity is an entity that cannot exist in the database without (and is logically dependent upon) another type of entity also existing in the database.
Q: ID-dependent entities are associated by a nonidentifying relationship.
Q: An ID-dependent entity is an entity whose identifier includes the identifier of another entity.
Q: E-R models use an identifying relationship to connect entities that are ID-dependent.
Q: An entity that represents something that can exist on its own is called a strong entity.
Q: In an E-R model, the three types of minimum cardinality are mandatory, optional, and indeterminate.
Q: An entity's minimum cardinality in a relationship indicates whether or not an entity must participate in the relationship.
Q: An entity's minimum cardinality in a relationship indicates the number of entity instances that must participate in the relationship.
Q: In a 1:N relationship, the parent entity is on the one side of the relationship, and the child entity is on the many side of the relationship.
Q: In a 1:N relationship, the term parent refers to the N side of the relationship.
Q: In an E-R model, the three types of maximum cardinality are 1:1, 1:N, and N:M.
Q: A relationship's maximum cardinality indicates the maximum number of entities that can participate in the relationship.
Q: Relationships are classified by their cardinality.
Q: The notation 1:N shows a relationship's maximum cardinalities.
Q: When designing a database, first identify the entities, then determine the attributes, and finally create the relationships.
Q: The principal difference between an entity and a table is that you can express a relationship between entities without using foreign keys.
Q: When transforming a data model into a relational design, relationships of all degrees are treated as combinations of binary relationships.
Q: The degree of a relationship is expressed as the relationship's maximum cardinality.
Q: A binary relationship is a relationship based on numerical entity instance identifiers.
Q: A single relationship class involves only one entity class.
Q: In today's E-R models, attributes of relationships are still used.
Q: E-R modeling recognizes both relationship classes and relationship instances.
Q: Relationships of degree two are referred to as binary relationships.
Q: A binary relationship is a relationship between two or more entities.
Q: The degree of a relationship is the number of entity classes in the relationship.
Q: Entities can be associated with one another in relationships.
Q: An identifier serves the same role for a table that a key does for an entity.
Q: A composite identifier is defined as a composite attribute that is an identifier.
Q: An identifier of an entity instance must consist of one and only one attribute.
Q: In E-R modeling, entities within an entity class may have different attributes.
Q: In E-R modeling, an attribute describes the characteristics of an entity.
Q: A compound identifier is an identifier consisting of two or more attributes.
Q: An identifier of an entity instance is one or more attributes that name or identify entity instances.
Q: An entity instance of an entity class is the representation of a particular entity and is described by the values of the attributes of the entity.
Q: An entity instance is an occurrence of a particular entity.
Q: An entity class is described by the structure of the entities in that class.
Q: Entities of a given type are grouped into entity classes.
Q: An entity is something that users want to track.
Q: The method of constructing data models used in the text is the extended entity-relationship (E-R) model.
Q: A data model is a plan for a database design.
Q: What are general-purpose remarks columns, and why are they a problem?
Q: What are null values, and why are they a problem?
Q: What are inconsistent values, and why are they a problem?
Q: What is the multivalue, multicolumn problem, and why is it a problem? Include an example.
Q: Explain denormalization, and why it may be appropriate to denormalize a set of tables.
Q: What are the advantages and disadvantages of normalization?
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