Q&A Hero

Q: Recursive M:N relationships are represented with an intersection table that shows pairs of related rows from a single table.

Q: When transforming an extended E-R model into a relational database design, recursive relationships are treated fundamentally the same as other HAS-A relationships.

Q: When transforming supertype/subtype entities into a relational database design, all of the attributes for the supertype table are placed into the subtype relations.

Q: Discriminator attributes can be represented in relational designs.

Q: To represent an IS-A relationship in a relational database design, the IS-A relationship must be converted into a HAS-A relationship.

Q: When transforming supertype/subtype entities into a relational database design, the key of the supertype table is placed into the subtype table typically as the key.

Q: When transforming supertype/subtype entities into a relational database design, an entity is created for the supertype only.

Q: When transforming an ID-dependent E-R data model relationship into a relational database design where the child entity is designed to use a surrogate key, the relationship changes to a weak but not ID-dependent relationship.

Q: The design transformation for all IS-A relationships can be summarized by the phrase "place the key of the parent table in the child table."

Q: When creating a table for an ID-dependent entity, both the key of the parent and the key of the entity itself must appear in the table.

Q: All identifying relationships are 1:N.

Q: An ID-dependent table can be used to represent multivalued attributes.

Q: Association tables sometimes connect more than two entities.

Q: Like all ID-dependent relationships, the parents of an association table are required.

Q: An intersection table can have additional attributes besides the keys of its parent tables.

Q: An intersection table is always ID-dependent on both of its parent tables.

Q: In many-to-many relationships in a relational database design,the primary keys of both tables are joined into a composite primary key in the intersection table.

Q: A key of an intersection table is always the combination of the keys of both parents.

Q: To represent an N:M relationship in a relational database design, in essence it is reduced to two 1:N relationships.

Q: To represent an N:M relationship in a relational database design, an intersection table is created.

Q: To represent an N:M relationship in a relational database design, a table is created to represent the relationship itself.

Q: To represent a one-to-many relationship in a relational database design, the key of the child table is placed as a foreign key into the other table.

Q: In 1:N relationships, the table on the "many" side is called the child.

Q: To represent a 1:N relationship in a relational database design, an intersection table is created.

Q: In representing a 1:N relationship in a relational database design, the key of the table representing the entity on the "many" side is placed as a foreign key in the table representing the entity on the "one" side of the relationship.

Q: In representing a 1:N relationship in a relational database design, the key of the table representing the parent entity is placed as a foreign key in the table representing the child entity.

Q: In 1:N relationships, the table on the "one" side is called the parent.

Q: In a 1:N relationship, the term parent refers to the table on the "many" side of the relationship.

Q: In a 1:1 relationship, the foreign key is defined as an alternate key to make the DBMS enforce uniqueness.

Q: When placing a foreign key for a 1:1 relationship, the key of either table can be used as the foreign key in the other table.

Q: To represent a 1:1 binary relationship in a relational database design, the key of one table is placed into the second table.

Q: When the key of one table is placed into a second table to represent a relationship, the key is called a relational key in the second table.

Q: In a relational database design, all relationships are expressed by creating a foreign key.

Q: A foreign key is a key that does not belong in any table.

Q: One of the important properties of a column is whether or not it can have a NULL value.

Q: The last step in creating a table is to verify table normalization.

Q: A data constraint is a limitation on data values.

Q: A default value is the value the user enters into the row the first time the user enters data.

Q: Data types are consistent across all DBMS products.

Q: A null value is an attribute value that has been set to zero.

Q: Whether or not an attribute is required is determined during the database modeling phase.

Q: A surrogate key should be considered when the key contains a lengthy text field.

Q: The values of a surrogate key have no meaning to the users.

Q: A surrogate key is a unique, system-supplied identifier used as the primary key of a table.

Q: One of the important properties of an attribute is whether or not it is required.

Q: A surrogate key is appropriate when the primary key of a table contains a lengthy text field.

Q: The ideal primary key is short, numeric, and fixed.

Q: By default, the identifier of the entity becomes the foreign key of the corresponding table.

Q: When creating a table in the relational database design from an entity in the extended E-R model, the attributes of the entity become the rows of the table.

Q: An entity needs to be examined according to normalization criteria before creating a table from it in the relational database design.

Q: Each entity in the extended E-R model is represented as a table in the relational database design.

Q: What are supertype and subtype entities? Include an example.

Q: Explain the ambiguity in the broad definition of a weak entity.

Q: What is an ID-Dependent entity? Include an example.

Q: Distinguish between entity identifiers and keys.

Q: How is minimum cardinality expressed in IE Crow's Foot E-R diagrams?

Q: How is maximum cardinality expressed in IE Crow's Foot E-R diagrams?

Q: What is meant by the cardinality of a relationship?

Q: What is meant by the degree of a relationship?

Q: Distinguish between an entity class and an entity instance.

Q: Describe and discuss the main elements of the Entity-Relationship (E-R) model. Include an example.

Q: Suppose you have created a data model for an airline based on a variety of forms, reports, user interviews, data sources, etc. Your client comes forward with a new desired report that includes passenger weights and a relationship between passengers and employees, neither of which is in your E-R diagram. You should ________. A) create a new, separate E-R diagram with just the new information B) add the relationship and the weight attribute to the existing data model C) add the relationship but not the weight attribute D) add the weight attribute but not the relationship

Q: Recursive relationships can have all of the following maximum cardinalities except ________. A) 1:1 B) 1:N C) N:M D) M:M

Q: When an entity has a relationship to itself, we have a(n) ________. A) supertype/subtype relationship B) archetype/instance relationship C) recursive relationship D) Both A and C are correct

Q: A for-use-by pattern must involve what kind of entity? A) Strong entity B) Supertype entity C) Weak entity with one identifying relationship D) Weak entity with two identifying relationships

Q: A line-item pattern must involve what kind of entity? A) Strong entity B) Supertype entity C) Weak entity with one identifying relationship D) Weak entity with two identifying relationships

Q: To represent an archetype/instance pattern in an E-R model, ________. A) create a new ID-dependent entity with a 1:N relationship B) create a new weak, but not ID-dependent entity with a 1:N relationship C) create a new strong entity with a 1:1 relationship D) create a new ID-dependent entity with a 1:1 relationship

Q: To represent a multivalued attribute in an E-R model, ________. A) create a new ID-dependent entity with a 1:N relationship B) create a new weak, but not ID-dependent entity with a 1:N relationship C) create a new strong entity with a 1:1 relationship D) create a new ID-dependent entity with a 1:1 relationship

Q: To represent an association pattern in an E-R model, ________. A) create a new ID-dependent entity with a 1:1 relationship to one other entity B) create a new weak, but not ID-dependent entity with a 1:1 relationship to one other entity C) create a new strong entity with a 1:1 relationship to one other entity D) create a new ID-dependent entity with a N:1 relationships to two parent entities

Q: Supertype/subtype entities are said to have a(n) ________ relationship. A) HAS-A B) IS-A C) recursive D) redundant

Q: Discriminators can be ________. A) attributes B) entities C) relationships D) subtypes

Q: An attribute that determines which subtype should be used is a(n) ________. A) supertype B) subtype C) discriminator D) identifier

Q: Which of the following is not true about subtype entities? A) Subtypes may be exclusive. B) The supertype and subtypes will have the same identifier. C) Subtypes are used to avoid a situation in which some attributes are required to be null. D) All subtypes of a supertype must have the same attributes.

Q: An entity that holds specialized attributes that distinguish it from one or more other similar entities is a ________. A) supertype B) subtype C) discriminator D) parent

Q: Which of the following is considered to be a weak entity? A) A subtype entity B) The archetype in an archetype/instance pattern C) The association entity in an association pattern D) The parent entity in a parent-child relationship

Q: An entity whose existence depends on the presence of another entity but whose identifier does not include the identifier of the other entity is a(n) ________. A) strong entity B) weak entity C) ID-dependent entity D) subtype entity

Q: An entity whose identifier includes the identifier of another entity is a(n) ________. A) strong entity B) weak entity C) optional entity D) required entity

Q: You are given an E-R diagram with two entities, ORDER and CUSTOMER, as shown above. What does the symbol next to the CUSTOMER entity indicate? 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: You are given an E-R diagram with two entities, ORDER and CUSTOMER, as shown above. What does the symbol next to the ORDER entity indicate?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: A circle 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"