Q&A Hero

Humanities

Q: In a relational database design, all relationships are expressed by ________. A) creating a primary key B) creating a foreign key C) creating a supertype D) creating a subtype
Q: Which of the following is not true about a NULL attribute? A) On insertion, entering the data for that field is optional. B) It is an important property of an attribute. C) It must have a default value specified. D) A primary key can't be NULL.
Q: Which of the following is not true about surrogate keys? A) They are identifiers that are supplied by the system, not the users. B) They have no meaning to the users. C) They are non-unique within a table. D) They can be problematic when combining databases.
Q: A surrogate key should be considered when ________. A) A relationship is N:M B) A composite key is required C) The key contains a lengthy text field D) The key contains a number
Q: Which of the following is not true for an ideal primary key? A) a composite of several long attributes B) numeric C) fixed D) short
Q: The identifier of the entity becomes the ________ of the corresponding table. A) primary key B) foreign key C) supertype D) subtype
Q: Each attribute of an entity becomes a(n) ________ of a table. A) column B) primary key C) foreign key D) alternate key
Q: The first step in transforming an extended E-R model into a relational database design is to ________. A) create a table for each relationship B) evaluate the entities against the normalization criteria C) create a table for each entity D) remove any recursive relationships
Q: Which of the following is not a step in the database design process? A) Create tables and columns from entities and attributes B) Select primary keys C) Represent relationships D) Create constraints and triggers
Q: It is easy to enforce the referential integrity actions for M-M relationships.
Q: When the child entity is required (M) in a relationship, there needs to be at least one child row for each parent row at all times.
Q: When the parent entity has a surrogate key, the enforcement actions are the same for both parent and child.
Q: If the parent is required, then a new child row must be created with a valid foreign key value.
Q: Cascading deletions are generally not used with relationships for weak child entities.
Q: Cascading deletions are generally not used with relationships between strong entities.
Q: When the parent entity is required (M) in a relationship, every row of the child table must have a valid, non-null value of the foreign key.
Q: A referential integrity constraint policy that insures that all rows containing a particular foreign key value in a table are eliminated from the table when the row containing the corresponding primary key value in a parent table is eliminated from the database is called cascading deletes.
Q: A referential integrity constraint policy that insures that foreign key values in a table are correctly maintained when there is a change to the primary key value in the parent table is called cascading insertions.
Q: Referential integrity constraints should disallow adding a new row to a child table when the foreign key does not match a primary key value in the parent table.
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.
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