Chapter 3 DBMgmt

11) If a 1:M relationship is optional on the M side and mandatory on the 1 side, and if the table resulting from the 1 side has 3 records, then the table resulting from the M side CANNOT have less than ________ records. A) 0 B) 1 C) 2 D) 3

0

12) If a 1:M relationship is optional on both sides, and if the table resulting from the 1 side has 3 records, then the table resulting from the M side CANNOT have less than ________ records. A) 0 B) 1 C) 2 D) 3

0

15) If an M:N relationship is optional on both sides, and if both relations resulting from the entities involved in the relationship each have 3 records, then the resulting bridge relation cannot have less than ________ records. A) 0 B) 1 C) 3 D) 9

0

18) If an entity has three unique attributes, how many primary keys will its mapped relation have? A) 0 B) 1 C) 2 D) 3

1

21) A relation resulting from a weak entity has a non-composite primary key when the identifying relationship is: A) Optional on both sides B) 1:1 C) 1:M D) M:N

1:1

10) If a 1:M relationship is mandatory on the M side and optional on the 1 side, and if the table resulting from the 1 side has 3 records, then the table resulting from the M side cannot have less than ________ records. A) 0 B) 1 C) 2 D) 3

3

13) If a 1:M relationship is mandatory on both sides, and if the table resulting from the 1 side has 3 records, then the table resulting from the M side CANNOT have less than ________ records. A) 0 B) 1 C) 2 D) 3

3

16) If an M:N relationship is mandatory on both sides, and if both relations resulting from the entities involved in the relationship each have 3 records, then the resulting bridge relation cannot have less than ________ records. A) 0 B) 1 C) 3 D) 9

3

17) If an M:N relationship is mandatory on one side and optional on the other side, and if both relations resulting from the entities involved in the relationship each have 3 records, then the resulting bridge relation cannot have less than ________ records. A) 0 B) 1 C) 3 D) 9

3

19) An entity with two multivalued attributes will be mapped as how many relations? A) 1 B) 2 C) 3 D) 4

3

20) An ER diagram that contains two entities involved in two separate M:N relationships will be mapped as how many relations? A) 1 B) 2 C) 3 D) 4

4

14) Which of the following is NOT true? Mapping an M:N relationship that has no attributes will result in: A) A new relation B) Two foreign keys C) A composite primary key D) A foreign key in both of the relations mapped from the involved entities

a foreign key in both of the relations mapped from the involved entities

22) Autonumber data type option: A) Automatically converts the existing data type into a number type B) Assigns a number to each of the used data types C) Enables automatic generation of consecutive numeric data values in a column D) Enables automatic counting of columns in a table

enables automatic generation of consecutive numeric data values in a column

5) Which of the following statements regarding the table below is true? Column A Column B Column C {view in book} A) Every value in Column A is unique B) Every value in Column B is unique C) Every combination of values in Column A and Column B within the same row is unique D) All of the above

every combination of values in column A and column B

10) A foreign key column must have the same name as the primary key column it refers to. true or false

false

12) When an entity has multiple unique attributes, each one of them is mapped as a primary key of the resulting relation. true or false?

false

15) An entity and its M:N unary relationship are mapped as one relation.

false

17) Each weak entity has one owner entity. true or false?

false

18) "For each employee middle initial is optional" is an example of an implicit database constraint. true or false?

false

2) Two columns of a relational table can have the same names. true or false?

false

5) Within one relation, two rows can be identical. true or false?

false

6) A row of a relation can have in its column two values from the column's domain. true false

false

7) If one of two identical relational tables has the first row moved to the last place, those two relational tables are no longer identical. true or false

false

8) If one of two identical relational tables has the last column row moved to the first place, those two relational tables are no longer identical. true or false?

false

9) An optional attribute of an entity is not mapped as a column of a relation. true or false

false

1) Tuple is a synonym for A) Column B) Field C) Row D) Table

row

2) Relation is a synonym for A) Column B) Field C) Row D) Table

table

If a 1:M relationship is optional on both sides, which of the following is true? A) The resulting foreign key can have null (empty) values B) The resulting foreign key cannot have null (empty) values C) The resulting foreign key must have null (empty) values D) No foreign key is created as a result of mapping such a relationship

the resulting foreign key can have null (empty) values

If a 1:M relationship is optional on the 1 side and mandatory on the M side, which of the following is true? A) The resulting foreign key can have null (empty) values B) The resulting foreign key cannot have null (empty) values C) The resulting foreign key must have null (empty) values D) No foreign key is created as a result of mapping such a relationship

the resulting foreign key can have null (empty) values

If a 1:M relationship is mandatory on both sides, which of the following is true? A) The resulting foreign key can have null (empty) values B) The resulting foreign key cannot have null (empty) values C) The resulting foreign key must have null (empty) values D) No foreign key is created as a result of mapping such a relationship

the resulting foreign key cannot have null (empty) values

If a 1:M relationship is mandatory on the 1 side and optional on the M side, which of the following is true? A) The resulting foreign key can have null (empty) values B) The resulting foreign key cannot have null (empty) values C) The resulting foreign key must have null (empty) values D) No foreign key is created as a result of mapping such a relationship

the resulting foreign key cannot have null (empty) values

1) A relational schema is a visual depiction of the relational database model. true or false?

true

11) A bridge relation is a result of mapping an M:N relationship.

true

13) An entity and its 1:1 unary relationship are mapped as one relation. true or false

true

14) An entity and its 1:M unary relationship are mapped as one relation.

true

16) The relation resulting from mapping a weak entity (with a 1:M identifying relationship) has a composite primary key that is composed of the partial identifier and a foreign key corresponding to the primary key of the owner entity. true or false?

true

19) A restriction specifying that no salary entered in the salary column can be higher than $300,000 is an example of a business rule. true or false?

true

20) Every attribute appears only once in an ER diagram. true or false?

true

3) Two columns of a relational table can have the same values. true or false?

true

4) Two columns of two different tables in the same relational database can have the same names. true or false?

true

4) Which of the following is NOT true? In a relational table: A) Two columns can have the same values B) All column names are different C) Two rows can have the same values D) All values in a column are from the same domain

two rows can have the same values

3) Which of the following is NOT true? In a relational database: A) Two tables can be a part of the same database B) Two tables can have the same number of columns C) Two tables can have the same number of rows D) Two tables can have the same names

two tables can have the same names