DBMS CH06

Which of the following is not true about representing subtypes in a relational database design?

All of the attributes of the supertype are added to the subtype relations.

Which of the following is not a step in the database design process?

Create constraints and triggers

Which of the following is not true of recursive relationships?

Even when the relationship is 1:N, a new table must be defined to represent the relationship.

When transforming an E-R data model into a relational database design, the key of the parent entity should be placed as part of the primary key into the child entity ________.

when the child entity is ID-dependent

Which of the following is not true of ternary relationships?

Must involve at least one M:N relationship

The binary constraint MUST COVER indicates that ________.

a binary relationship includes a set of value combinations that must all occur in a ternary relationship

The binary constraint MUST NOT indicates that ________.

a binary relationship includes value combinations that must not occur in a ternary relationship

Many-to-many relationships are represented by ________.

an intersection table which has 1:N relationships with the two tables

In a supertype-subtype structure, discriminator attributes ________.

cannot be represented in a relational design require application logic to determine which subtypes correspond to a specific supertype instance

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

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 updates

Each attribute of an entity becomes a(n) ________ of a table.

column

In relational database design, ID-dependent entities are used to ________.

handle associative relationships handle multivalued attributes represent N:M relationships handle archetype/instance relationships

A referential integrity constraint policy that guarantees that a row in a parent table always has a required entry in a child table ________.

is known as a minimum cardinality enforcement action needs to be documented by the database development team

When transforming an ID-dependent E-R data model relationship into a relational database design, the referential integrity constraints should allow ________.

parent updates to cascade

The identifier of the entity becomes the ________ of the corresponding table.

primary key

One of the important properties of a column is whether or not it is ________.

required

When transforming an ID-dependent E-R data model relationship into a relational database design and the child entity is designed to use a surrogate key, then ________.

the relationship changes to a non-ID-dependent relationship

Which of the following is not true about surrogate keys?

They are nonunique within a table.

To which of the following actions are referential integrity constraints not applied?

create

The first step in transforming an extended E-R model into a relational database design is to ________.

create a table for each entity

In a relational database design, all relationships are expressed by ________.

creating a foreign key

The ideal primary key is ________.

numeric short fixed

In many-to-many relationships in a relational database design ________.

the intersection table is ID-dependent on both of the parents the minimum cardinality from the intersection table to the parents is always 1

A surrogate key should be considered when ________.

the key contains a lengthy text field

When representing a 1:1 relationship in a relational database design ________.

the key of either table may be placed as a foreign key into the other

To represent a one-to-many relationship in a relational database design ________.

the key of the parent is placed as a foreign key into the child

In many-to-many relationships in a relational database design ________.

the keys of both tables are placed in a third table the keys of both tables are joined into a composite key

When representing a one-to-many relationship in a relational database design ________.

the parent is always on the one side of the 'one-to-many' relationship

When transforming an ID-dependent E-R data model relationship into a relational database design and the parent entity has a surrogate primary key and the child entity has a data identifier, then the primary key of the child table should be ________.

the parent's surrogate key + the child's data key the parent's surrogate key + a surrogate key in the child