ISDS 402 - Chapter 5
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
A) Association relationship
Microsoft Access does not create N:M relationships because:
A) Microsoft Access creates databases based on database designs instead of data models.
Given the tables TABLE_A (Attribute1, Attribute2, Attribute3) TABLE_B (Attribute4, Attribute5, Attribute6) as shown in the figure below, which of the following would display the correct placement of foreign keys in the relational model?
A) TABLE_A (Attribute1, Attribute2, Attribute3) TABLE _B (Attribute4, Attribute5, Attribute6, Attribute1)
Which of the following is the correct technique for representing a 1:N relationship in the relational model? A) The key of the entity on the one side is placed into the relation for the entity on the many side. B) The key of the child is placed into the relation of the parent. C) The key of either relation can be placed into the other relation. D) The key of the entity on the many side is placed into the relation for the entity on the one side. E) An intersection relation is created, and the keys from both parent entities are placed as keys in the intersection relation.
A) The key of the entity on the one side is placed into the relation for the entity on the many side.
Each attribute of an entity becomes a(n) ________ of a table.
A) column
The identifier of the entity becomes the ________ of the corresponding table.
A) primary key
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
In many-to-many relationships in a relational database design, ________. 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 minimum cardinality from the intersection table to the parents is always M D) A and B E) B and C
Answer: E
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 tables are joined into a composite key E) C and D
Answer: E
57) By default, when Microsoft Access creates a relationship between two tables, it creates a(n):
B) 1:N relationship.
Which of the following is not true about representing subtypes in a relational database design?
B) All of the attributes of the supertype are added to the subtype relations.
In a relational database design, all relationships are expressed by ________.
B) creating a foreign key
One of the important properties of a column is whether or not it is ________.
B) required
What relationship pattern is illustrated in the following schema? EMPLOYEE (EmployeeID, OfficePhone, Manager) Manager in EMPLOYEE must exist in EmployeeID in EMPLOYEE
C) Recursive relationship
Which of the following is true when representing a 1:1 binary relationship using the relational model? A) The key of the entity with the highest minimum cardinality must be placed in the other entity as a foreign key. B) The key of each entity must be placed in the other as a foreign key. C) The key of either entity is placed in the other as a foreign key. D) The key of the entity with the most attributes must be placed in the other entity as a foreign key. E) Both entities must have the same primary key.
C) The key of either entity is placed in the other as a foreign key.
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 nonunique within a table. D) They can be problematic when combining databases. E) The DBMS will not allow their values to be changed.
C) They are nonunique within a table.
The first step in transforming an extended E-R model into a relational database design is to
C) create a table for each entity
In relational database design, ID-dependent entities are used to ________.
C) represent N:M relationships
58) To create a 1:1 relationship between two tables in Microsoft Access:
C) the Indexed property of the foreign key column must be set to Yes (No Duplicates).
A surrogate key should be considered when ________.
C) the key contains a lengthy text field
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 ________.
C) the relationship changes to a non-ID-dependent relationship
Which of the following is true about representing a weak entity with the relational model? A) If the weak entity is existence-dependent, the key of the parent must be part of the key of the weak entity. B) If the strong entity has a minimum cardinality of 1, the key of the weak entity must be part of the strong entity. C) If the weak entity is ID-dependent, the key of the weak entity must be part of the key of the parent entity. D) If the weak entity is ID-dependent, the key of the parent entity must be part of the key of the weak entity. E) If the parent entity is existence-dependent, then the minimum cardinality of the weak entity is zero.
D) 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? A) Relax security B) Lack of design time C) End user preference D) Improve performance E) None of the above
D) Improve performance
56) As far as Microsoft Access is concerned, there are no:
D) N:M relationships.
65) 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 key.
ID-dependent
64) To represent a many-to-many relationship in the relational model, a(n) ________ table is used.
intersection
61) Once a table has been defined, it should be examined according to ________ criteria.
normalization
66) A(n) ________ is a relationship among entities of the same class.
recursive relationship
Microsoft Access uses the same pure N:M relationships that occur in data modeling.
FALSE
Relations should always be normalized to the highest degree possible.
FALSE
Relationships that are 1:1 do not require referential integrity constraints.
FALSE
The first step in representing entities using the relational model is to determine which identifier will be used as the key.
FALSE
The key of the parent entity becomes part of the key of an ID-dependent entity.
FALSE
The technique for representing E-R relationships in the relational model is dependent on the minimum cardinality.
FALSE
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.
FALSE
When applied to 1:N relationships, the term "parent" refers to the many side of the relationship since a child may have many parents.
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
The ideal primary key is ________. A) short B) numeric C) fixed D) A and B E) A, B, and C
E
Which of the following is not true of recursive relationships?
E) Even when the relationship is 1:N, a new table must be defined to represent the relationship.
44) 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?
E) PRODUCT (ProductID, Description, Cost) SUPPLIER (SupplierID, ContactName, PhoneNumber) PRODUCT_SUPPLIER (ProductID, SupplierID)
2) 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?
E) PRODUCT (ProductID, Description, Cost, SupplierID) SUPPLIER (SupplierID, ContactName, PhoneNumber)
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
E) Supertype/subtype relationship
59) After a 1:1 relationship has been created between two tables in Microsoft Access, the Relationship Type of One-To-One appears:
E) in the Edit Relationships dialog box.
All recursive relationships are 1:1.
FALSE
An entity needs to be examined according to normalization criteria before creating a table from it in the relational database design.
FALSE
As far as Microsoft Access is concerned, there are no 1:N relationships.
FALSE
By default, Microsoft Access creates 1:1 relationships between tables.
FALSE
By default, the identifier of the entity becomes the foreign key of the corresponding table.
FALSE
For a 1:1 relationship, the key of each table should be placed in the other table as the foreign key.
FALSE
If a weak entity is ID-dependent but not existence-dependent, it can be represented using the same techniques as a strong entity.
FALSE
63) To normalize a relation, the determinant of every functional dependency should be a(n) ________.
candidate key
62) There are cases where it is possible to normalize a table too far, in which case there may be a need for ________.
denormalization
60) The first step of database design is to define a table for each ________.
entity
