chapter 6
false
In a 1:N relationship, the term "parent" refers to the table on the "many" side of the relationship.
true
The key of an intersection table is always the combination of the keys of both parents.
false
A default value is the value the user enters into the row the first time the user enters data.
false
A foreign key is a key that does not belong in any table.
false
A null value is an attribute value that has been set to zero.
cascading deletes
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 updates
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 __________.
true
A surrogate key is appropriate when the primary key of a table contains a lengthy text field.
lengthy text field
A surrogate key should be considered when the key contains a(n) __________ .
surrogate
A(n) __________ key is a unique, system-supplied identifier used as the primary key of a table.
true
An ID-dependent table can be used to represent multivalued attributes.
ID-dependent
An ________table can be used to represent multivalued attributes.
false
An entity needs to be examined according to normalization criteria before creating a table from it in the relational database design.
false
An intersection table can have additional attributes besides the keys of its parent tables.
true
An intersection table is always ID-dependent on both of its parent tables.
true
Association tables sometimes connect more than two entities.
primary key
By default, the identifier of the entity becomes the ________ of the corresponding table.
false
By default, the identifier of the entity becomes the foreign key of the corresponding table.
true
Deleting the children when the parent is deleted is known as cascading deletes.
true
If the parent is required, then a new child row must be created with a valid foreign key value.
child
In 1:N relationships, the foreign key is placed inside the________table.
child
In 1:N relationships, the table on the "many" side is called the ________.
parent
In 1:N relationships, the table on the "one" side is called the ________.
true
In a 1:1 relationship, the foreign key is defining as an alternate key to make the DBMS enforce uniqueness.
true
In a relational database design, all relationships are expressed by creating a foreign key.
foreign key
In a relational database design, all relationships are expressed by creating a(n) _________ .
composite primary key
In many-to-many relationships in a relational database design the primary keys of both tables are joined into a(n) __________ in the intersection table.
false
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.
true
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.
intersection
In representing a M:N relationship in a relational database design, a(n) __________ table is created.
false
It is easy to enforce the referential integrity actions for M-M relationships.
true
Like all ID-dependent relationships, the parents of an association table are required.
ID-dependent
Like all ________ relationships, the parents of an association table are required.
null value
One of the important properties of an attribute is whether or not it can have a _________.
true
One of the important properties of an attribute is whether or not it is required.
false
Propagating a change made to a parent's primary key to the children's foreign key is known as cascading changes.
true
Recursive M:N relationships are represented with an intersection table that shows pairs of related rows from a single table.
disallow
Referential integrity constraints should ________ adding a new row to a child table when the foreign key does not match a primary key values in the parent table.
supertype
The key of the subtypes will be the key of the ________ .
true
The last step in creating a table is to verify table normalization.
surrogate key
The values of a(n) __________ have no meaning to the users.
true
To represent a 1:1 binary relationship in a relational database design, the key of one table is placed into the second table.
false
To represent a 1:N relationship in a relational database design, an intersection table is created.
true
To represent a M:N relationship in a relational database design, a table is created to represent the relationship itself.
true
To represent a M:N relationship in a relational database design, an intersection table is created.
1:N
To represent a M:N relationship in a relational database design, in essence it is reduced to two _________ relationships.
the parent table
To represent a one-to-many relationship in a relational database design the key of ________ is placed as a foreign key into the other table.
false
To represent an IS-A relationship in a relational database design, the IS-A relationship must be converted into a HAS-A relationship.
true
When transforming an extended E-R model into a relational database design, recursive relationships are treated fundamentally the same as other HAS-A relationships.
false
When transforming supertype/subtype entities into a relational database design, all of the attributes for the supertype table are placed into the subtype relations.
false
When transforming supertype/subtype entities into a relational database design, an entity is created for the supertype only.
true
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.
false
Whether or not an attribute is required is determined during the database modeling phase.
association tables
_____________ sometimes connect more than two entities.
recursive relationships
__________are treated fundamentally the same as other HAS-A relationships.
discriminator
__________attributes cannot be represented in relational designs.
true
A data constraint is a limitation on data values.
true
Cascading deletions are generally not used with relationships between strong entities.
false
Cascading deletions are generally not used with relationships for weak child entities.
false
Data types are consistent across all DBMS products.
short, numeric, fixed
The ideal primary key is _______, _______and _______.
true
The ideal primary key is short, numeric, and fixed.
true
All identifying relationships are 1:N.
1:N
All identifying relationships are ___________.
false
When creating a relational database design from E-R diagrams, first create a relation for each relationship.
true
Each entity in the extended E-R model is represented as a table in the relational database design.
false
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."
verify normalization
The final step in the database design process of creating tables is to __________.
true
The first step in the database design process is to create tables and columns from entities and attributes.
parent
When creating a table for an ID-dependent entity, both the key of the _______ and the key of the entity itself must appear in the table.
false
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.
true
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.
either table
When representing a 1:1 relationship in a relational database design the key of ____________ may be placed as a foreign key into the other table.
true
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.
false
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.
false
When the parent entity has a surrogate key, the enforcement actions are the same for both parent and child.
true
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.
foreign key
When the primary key of one table is stored in another table, it is called a(n)________.
changes to a weak but not ID-dependent relationship
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 _____________ .
table
When transforming an extended E-R model into a relational database design, first create a(n)_________ for each entity.
