Chapter 3 (True/False)

Question 1

1) The practical significance of taking the logical view of a database is that is serves as  reminder of the simple file concept of data storage.

Answer

true

Question 2

2) You can think of a table as a persistent representation of a logical relation.

Answer

true

Question 3

3) Because the relational model uses attribute values to establish relationships among tables, many data-base susers correctly assume that the term relation refers to such relationships.

Answer

true

Question 4

4) The order of the rows and columns is important to the DBMS.

Answer

true

Question 5

5) Numeric data are data on which you can perform meaningful arithmetic procedures.

Answer

true

Question 6

6) Character data can contain any character or symbol intended for mathematical manipulation.

Answer

true

Question 7

7) Each table in a relational database must have a primary key.

Answer

true

Question 8

8) The idea of determination is unique to the database environment.

Answer

true

Question 9

9) In a relational model, if A determines B, C, and D, you write A = B, C, D.

Answer

true

Question 10

10) Only a single attribute, not multiple attributes, can define functional dependence.

Answer

true

Question 11

11) If the attribute (B) is functionally dependent on a composite key (A) but not on any subset of that composite key, the attribute (B) is fully functionally dependent on (A).

Answer

true

Question 12

12) A null is created when you press the Enter key or the Tab key to move to the next entry without making a prior entry of any kind.

Answer

true

Question 13

13) There is never a good reason to use null values in  a database.

Answer

true

Question 14

14) Depending on the sophistication of the application development software, nulls can create problems when functions such as COUNT, AVERAGE, and SUM are used.

Answer

true

Question 15

15) Tables within a database share common attributes that enable the tables to be linked together.

Answer

true

Question 16

16) A foreign key must exist in both tables that have a relationship

Answer

true

Question 17

17) RDBMSs enforce integrity rules automatically.

Answer

true

Question 18

18) Referential and entity integrity are two names for the same thing.

Answer

true

Question 19

19) The SELECT operator yields a vertical subset of a table.

Answer

true

Question 20

20) Tables must have the same attribute characteristics (the columns and domains must be compatible) to be used in a UNION.

Answer

true

Question 21

21) The DIFFERENCE operator subtracts one table from the other.

Answer

true

Question 22

22) In a natural join, the column on which the join was made occurs twice in the new table.

Answer

true

Question 23

23) A left outer join on tables CUSTOMER and AGENT yields all of the rows in the CUSTOMER table, including those that do not have a matching value in the AGENT table.

Answer

true

Question 24

24) The DIVIDE operation uses one single-column table (e.g., column "a") as the divsor and one two-column table (e.g., columns "a" and "b") as the dividend.

Answer

true

Question 25

25) A data dictionary contains metadata-data about data.

Answer

true

Question 26

26) A data dictionary is sometimes described as :the database designer's database" because it records the design decisions about tables and their structures.

Answer

true

Question 27

27) Current relational database software generally provides only a system catalog (and not a data dictionary).

Answer

true

Question 28

28) The one-to-many (1:M) relationship is easily implemented in the relational mode by putting the foreign key of the "1" side in the table of the "many" side as a primary key.

Answer

true

Question 29

29) As rare as 1:! relationships should be, certain conditions absolutely require their use.

Answer

true

Question 30

30) DBMSs use indexes for many different purposes.

Answer

true

Chapter 3 (True/False)

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