Data Base Chapter 3 Test 3 (Second set)
The first step in representing entities using the relational model is to determine which identifier will be used as the key.
F
The technique for representing E-R relationships in the relational model is dependent on the minimum cardinality.
F
To represent a 1:N relationship in the relational model, the key of either entity may be placed as a foreign key in the other entity.
F
When applied to 1:N relationships, the term "parent" refers to the many side of the relationship since a child may have many parents.
F
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.
F
As far as Microsoft Access is concerned, there are no N:M relationships.
T
By default, when Microsoft Access creates a relationship between two tables it creates a(n) ________ relationship.
1:N
By default, when Microsoft Access creates a relationship between two tables, it creates a(n) ________.
1:N relationship
Which of the following is the correct technique for representing a M:N relationship using the relational model?
An intersection relation is created, and the keys of both parent entities are placed as a composite key in the intersection relation.
) What relationship pattern is illustrated in the following schema? PRODUCT (ProductID, Description) SUPPLIER (SupplierID, ContactName, PhoneNumber) PRODUCT_SUPPLIER (ProductID, SupplierID, Cost) ProductID in PRODUCT_SUPPLIER must exist in ProductID in PRODUCT SupplierID in PRODUCT_SUPPLIER must exist in SupplierID in PRODUCT
Association relationship
For a(n) ________ weak entity, it is necessary to add the key of the parent entity to the weak entity's relation so that this added attribute becomes part of the weak entity's
ID-dependent
Which of the following is true about representing a weak entity with the relational model?
If the weak entity is ID-dependent, the key of the parent entity must be part of the key of the weak entity.
Which of the following would be a reason to denormalize a relation?
Improve performance
What relationship pattern is illustrated in the following schema? EMPLOYEE (EmployeeID, OfficePhone, Manager)
Manager in EMPLOYEE must exist in EmployeeID in EMPLOYEE
) Microsoft Access does not create N:M relationships because ________.
Microsoft Access creates databases based on database designs instead of data models
As far as Microsoft Access is concerned, there are no ________.
N:M relationships
As far as Microsoft Access is concerned, there are no ________.
N:M relationships.
Which of the following is not true about representing subtypes in a relational database design?
Supertype/subtype relationship
) Given the tables PRODUCT (ProductID, Description, Cost) SUPPLIER (SupplierID, ContactName, PhoneNumber) as shown in the figure below, which of the following would represent the correct placement of foreign keys?
SupplierID in PRODUCT table
Which of the following is true when representing a 1:1 binary relationship using the relational model?
The key of either entity is placed in the other as a foreign key.____
Which of the following is not true about surrogate keys?
They are nonunique within a table.
What relationship pattern is illustrated in the following schema? VEHICLE (VehicleID, Cost) CAR (VehicleID, NumberOfSeats) TRUCK (VehicleID, CargoCapacity)
VehicleID in CAR must exist in VehicleID in VEHICLE VehicleID in TRUCK must exist in VehicleID in VEHICLE
Once a table has been defined, it should be examined according to ________ criteria.
_normalization
To create a 1:1 relationship between two tables in Microsoft Access ________.
_the Indexed property of the foreign key column must be set to Yes (No Duplicates
After a 1:1 relationship has been created between two tables in Microsoft Access, the Relationship Type of One-To-One appears ________.
in the Edit Relationships dialog box.
After a 1:1 relationship has been created between two tables in Microsoft Access, the Relationship Type of One-To-One appears in the ________.
in the Edit Relationships dialog box.
To represent a many-to-many relationship in the relational model, a(n) ________ table is used.
intersection
The identifier of the entity becomes the ________ of the corresponding table
primary key
A(n) ________ is a relationship among entities of the same class
recursive relationship
One of the important properties of a column is whether or not it is ________.
required
To create a 1:1 relationship between two tables in Microsoft Access, the Indexed property of the foreign key column must be set to ________.
the Indexed property of the foreign key column must be set to Yes (No Duplicates).
) A surrogate key should be considered when ________.
the key contains a lengthy text field____
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
All recursive relationships are 1:1.
F
In relational database design, ID-dependent entities are used to ________.
All of the above.
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.
) By default, the identifier of the entity becomes the foreign key of the corresponding table.
F
An entity needs to be examined according to normalization criteria before creating a table from it in the relational database design.
F
As far as Microsoft Access is concerned, there are no 1:N relationships.
F
By default, Microsoft Access creates 1:1 relationships between tables.
F
For a 1:1 relationship, the key of each table should be placed in the other table as the foreign key.
F
If a weak entity is ID-dependent but not existence-dependent, it can be represented using the same techniques as a strong entity.
F
Microsoft Access uses the same pure N:M relationships that occur in data modeling.
F
Relations should always be normalized to the highest degree possible.
F
Relationships that are 1:1 do not require referential integrity constraints.
F
A surrogate key is appropriate when the primary key of a table contains a lengthy text field.
T
From a pragmatic standpoint, the only important rule of normalization is that the determinant of every functional dependency must be a candidate key.
T
In certain circumstances, there may be a preference as to which table in a 1:1 relationship contains the foreign key.
T
In the relational model, many-to-many relationships cannot be directly represented by relations the way 1:1 and 1:N relationships can.
T
Recursive relationships can be represented in the relational model using the same techniques that are used for binary relationships.
T
The ideal primary key is short, numeric, and nonchanging.
T
The key of the parent entity becomes part of the key of an ID-dependent entity.
T
To create a 1:1 relationship in Microsoft Access, the Indexed property of the foreign key column must be set to Yes (No Duplicates).
T
To represent a 1:N relationship in the relational model, the key of the entity on the one side of the relationship is placed as a foreign key in the entity on the many side of the relationship.
T
To represent a M:N relationship in the relational model, an intersection table is created to represent the relationship itself.
T
Which of the following is the correct technique for representing a 1:N relationship in the relational model?
TABLE_A (Attribute1, Attribute2, Attribute3) TABLE _B (Attribute4, Attribute5, Attribute6, Attribute1)
To normalize a relation, the determinant of every functional dependency should be a(n) ________.
candidate key
Each attribute of an entity becomes a(n) ________ of a table.
column_______
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
Microsoft Access does not create N:M relationships because Microsoft Access creates databases based on ________.
database designs_______
There are cases where it is possible to normalize a table too far, in which case there may be a need for
denormalization
The first step of database design is to define a table for each ________.
entity
