ise 224
A database design is a set of database specifications that can actually be implemented as a data model.
FALSE
A default value is the value the user enters into the row the first time the user enters data.
FALSE
A null value is an attribute value that has been set to zero.
FALSE
A referential integrity constraint policy that insures 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 a cascading insertion.
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.
FALSE
By default, the identifier of the entity becomes the foreign key of the corresponding table.
FALSE
Cascading deletions are generally not used with relationships for weak child entities.
FALSE
Data types are consistent across all DBMS products
FALSE
Discriminator attributes can be represented in relational designs.
FALSE
In a 1:N relationship, the term parent refers to the table on the "many" side of the relationship.
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.
FALSE
It is easy to enforce the referential integrity actions for N:M relationships
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."
FALSE
To represent a 1:N relationship in a relational database design, an intersection table is created.
FALSE
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.
FALSE
To represent an IS-A relationship in a relational database design, the IS-A relationship must be converted into a HAS-A relationship
FALSE
When creating a relational database design from E-R diagrams, first create a relation for each relationship
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.
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
FALSE
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.
FALSE
A foreign key is a key that is used as a surrogate key.
FALSER
A data constraint is a limitation on data values
TRUE
A key of an intersection table is always the combination of the keys of both parents.
TRUE
A referential integrity constraint policy that insures that all rows containing a 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.
TRUE
A surrogate key is a unique, system-supplied identifier often used as the primary key of a table.
TRUE
A surrogate key is appropriate when the primary key of a table contains a lengthy text field.
TRUE
A surrogate key should be considered when the key contains a lengthy text field.
TRUE
All identifying relationships are 1:N.
TRUE
An ID-dependent table can be used to represent multivalued attributes
TRUE
An alternate key and a candidate key describe the same attributes in a table.
TRUE
An intersection table is always ID-dependent on both of its parent tables.
TRUE
Association tables sometimes connect more than two entities.
TRUE
Cascading deletions are generally not used with relationships between strong entities
TRUE
Each entity in the extended E-R model is represented as a table in the relational database design
TRUE
If the parent is required, then a new child row must be created with a valid foreign key value.
TRUE
In 1:N relationships, the table on the "many" side is called the child.
TRUE
In 1:N relationships, the table on the "one" side is called the parent
TRUE
In a 1:1 relationship, the foreign key is defined 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.
TRUE
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.
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.
TRUE
Like all ID-dependent relationships, the parents of an association table are required.
TRUE
One of the important properties of a column is whether or not it can have a NULL value
TRUE
One of the important properties of an attribute is data type.
TRUE
Recursive M:N relationships are represented with an intersection table that shows pairs of related rows from a single table.
TRUE
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.
TRUE
The first step in the database design process is to create tables and columns from entities and attributes
TRUE
The ideal primary key is short, numeric, and fixed
TRUE
The last step in creating a table is to verify table normalization.
TRUE
The values of a surrogate key 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.
TRUE
To represent an N:M relationship in a relational database design, a table is created between the two tables to represent the relationship itself.
TRUE
To represent an N:M relationship in a relational database design, an intersection table is created.
TRUE
To represent an N:M relationship in a relational database design, in essence it is reduced to two 1:N relationships
TRUE
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.
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.
TRUE
When the child entity is required (M) in a relationship, there needs to always be at least one child row for each parent row.
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.
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
TRUE
Each attribute of an entity becomes a(n) ________ of a table. A) column B) primary key C) foreign key D) alternate key
A
In many-to-many relationships between strong entities in a relational database design, which of the following is not true? A) The intersection table is ID-dependent on one of the parents B) The intersection table is ID-dependent on both of the parents C) The relationships from the intersection table to the parent tables are identifying relationships D) The maximum cardinality to the intersection table is always N
A
The identifier of the entity becomes the ________ of the corresponding table. A) primary key B) foreign key C) supertype D) subtype
A
When representing a one-to-many relationship in a relational database design, ________. A) the parent is always on the one side of the "one-to-many" relationship B) the child is always on the one side of the "one-to-many" relationship C) either parent or child can be on the one side of the "one-to-many" relationship, and the choice is arbitrary D) either parent or child can be on the one side of the "one-to-many" relationship, and special criteria indicate which table should be on the one side
A
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 ________. A) when the child entity is ID-dependent B) when the child entity is non-ID-dependent C) when the child entity has a 1:1 relationship with the parent entity D) when the child entity has a 1:N relationship with the parent entity
A
When transforming an ID-dependent E-R data model relationship into a relational database design, the referential integrity constraints should allow ________. A) parent updates to cascade B) child updates to cascade C) child deletes to cascade D) Both A and B are correct
A
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
A
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 ________. A) incremental updates B) incremental deletes C) cascading updates D) cascading deletes
C
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
C
In many-to-many relationships in a relational database design, ________. A) the key of the child is placed as a foreign key into the parent B) the key of the parent is placed as a foreign key into the child C) the keys of both tables are placed in a third table D) the keys of both entity tables are placed in each other
C
In relational database design, ID-dependent entities are not used to ________. A) represent N:M relationships B) handle associative relationships C) represent relationships where the child identifier does not include the key of the parent D) handle archetype/instance relationships
C
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
C
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.
C
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.
C
) The binary constraint MUST NOT indicates that ________. A) a specific binary relationship must not be included in a ternary relationship B) a table includes values that must not occur in a binary relationship C) a table includes values that must not occur in a ternary relationship D) a binary relationship includes value combinations that must not occur in a ternary relationship
D
A referential integrity constraint policy that guarantees that a row in a parent table always has a required entry in a child table ________. A) is known as a minimum cardinality enforcement action B) needs to be documented by the database development team C) is enforced in most DBMS products D) Both A and B are correct
D
A referential integrity constraint policy that insures that all rows containing a 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 ________. A) incremental updates B) incremental deletes C) cascading updates D) cascading deletes
D
For the M-O (parent mandatory, child optional) case, what action(s) should be taken to ensure minimum cardinality is maintained? A) Define referential integrity constraint from child to parent B) Make foreign key NOT NULL C) Will require trigger or other application code D) Both A and B are correct
D
In a supertype-subtype structure, discriminator attributes ________. A) are easily represented in a relational design B) cannot be represented in a relational design C) require application logic to determine which subtypes correspond to a specific supertype instance D) Both B and C are correct
D
Many-to-many relationships are represented by ________. A) two tables with an M:N relationship B) two tables with a 1:N relationship C) an intersection table which has M:N relationships with the two tables D) an intersection table which has 1:N relationships with the two tables
D
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
D
Which of the following is not true about N:M recursive relationships? A) Both foreign keys in the intersection table refer to the same table. B) Since it is a recursive relationship, an intersection table is not needed. C) The foreign keys in the intersection table can't refer to the same attribute in the parent table. D) Both B and C are correct.
D
Which of the following is not true of recursive relationships? A) When the recursive relationship is M:N, an intersection table is created. B) The rows of a single table can play two different roles. C) Recursive relationships can be 1:1, 1:N, or M:N relationships. D) When the relationship is 1:N, a new table must be defined to represent the relationship.
D
Four uses for ID-dependent entities include all of the following except ________. A) representing N:M relationships B) representing intersection relationships C) storing multivalued attributes D) representing archetype/instance relationships
B
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
B
The binary constraint MUST COVER indicates that ________. A) a specific binary relationship must be included in a ternary relationship B) a binary relationship includes a set of value combinations that must all occur in a ternary relationship C) a table includes values that must occur in a binary relationship D) a table includes values that must occur in a ternary relationship
B
To represent a one-to-many relationship in a relational database design, ________. A) the key of the child is placed as a foreign key into the parent B) the key of the parent is placed as a foreign key into the child C) an intersection table must be created D) the key of the table on the "many" side is placed in the table on the "one" side
B
When representing a 1:1 relationship in a relational database design, ________. A) the key of each table must be placed as foreign keys into the other B) the key of either table may be placed as a foreign key into the other C) the key of both tables must be the same D) the intersection table gets the key from both relations
B
Which of the following is not true about representing subtypes in a relational database design? A) One table is created for the supertype and one for each subtype. B) All attributes of the supertype are added to the subtype relations. C) The key of the supertype is made the key of the subtypes. D) An instance of the supertype may be related to one instance each of several subtypes
B
Which of the following is not true of a MUST constraint? A) It may be needed in ternary relationships to enforce special business rules. B) It can be expressed directly in a relational model. C) It must be enforced by program code. D) It requires that one entity be combined with another entity.
B
