08

Topics: SQL, Data modeling, Foreign key Pages: 17 (4844 words) Published: April 15, 2015
Database Processing, 13e (Kroenke/Auer)
Chapter 8: Database Redesign

1) Database redesign is rarely needed because databases are usually built correctly the first time. Answer: FALSE
Diff: 1 Page Ref: 367

2) In a real sense, information systems and organizations do not just influence each other, but rather they create each other. Answer: TRUE
Diff: 1 Page Ref: 367

3) A continuous circular process of changes in user behaviors and change in the information systems they use is a natural outcome of information system use. Answer: TRUE
Diff: 1 Page Ref: 367

4) The continuous circular process of changes is known as the Systems Development Life Cycle (SDLC). Answer: TRUE
Diff: 1 Page Ref: 367

5) Database redesign is equally difficult whether or not the database has data in it. Answer: FALSE
Diff: 1 Page Ref: 367

6) In the database redesign process, it is often useful to test whether certain conditions or assumptions are valid before proceeding with the redesign. Answer: TRUE
Diff: 1 Page Ref: 3

7) In the database redesign process, two SQL tools are useful for testing whether or not certain conditions or assumptions are valid: uncorrelated subqueries and EXISTS/NOT EXISTS. Answer: FALSE
Diff: 2 Page Ref: 367

8) A correlated subquery looks very different from a noncorrelated subquery. Answer: FALSE
Diff: 2 Page Ref: 368

9) Correlated subqueries can be used to verify functional dependencies. Answer: TRUE
Diff: 2 Page Ref: 367-371

10) In a correlated subquery, the same table is used in the upper and lower SELECT statements. Answer: TRUE
Diff: 2 Page Ref: 368-370
11) In the SQL statement:

SELECT S1.CustName, S1.SalesRepNo FROM SALES S1;

the "S1" is called an alias.
Answer: TRUE
Diff: 2 Page Ref: 369

12) In a correlated subquery, the DBMS can run the lower SELECT statement by itself and then send the results to the upper SELECT statement. Answer: FALSE
Diff: 2 Page Ref: 368-370

13) In a correlated subquery, the DBMS must run the lower SELECT statement as a process that is nested within the upper SELECT statement. Answer: TRUE
Diff: 1 Page Ref: 368-370

14) There is a common trap in writing a correlated subquery, which will cause no rows to ever be displayed in the results. Answer: TRUE
Diff: 2 Page Ref: 370

15) Although correlated subqueries are useful in database redesign, they cannot be used to verify functional dependencies. Answer: FALSE
Diff: 1 Page Ref: 370-371

16) When using queries with EXISTS and NOT EXISTS, the processing of the associated SELECT statements must be nested. Answer: TRUE
Diff: 2 Page Ref: 371

17) The use of a double nested set of NOT EXISTS SELECT statements can be used to find rows that meet some specified condition for every row in a table. Answer: TRUE
Diff: 3 Page Ref: 372

18) The use of a double nested set of NOT EXISTS SELECT statements is a famous pattern in SQL use. Answer: TRUE
Diff: 2 Page Ref: 372

19) EXISTS and NOT EXISTS are actually just another form of correlated subqueries. Answer: TRUE
Diff: 1 Page Ref: 371

20) Because EXISTS and NOT EXISTS are forms of correlated subqueries, the processing of the associated SELECT statements must be nested. Answer: TRUE
Diff: 2 Page Ref: 371
21) The EXISTS keyword will be true if any row in the subquery meets the condition. Answer: TRUE
Diff: 2 Page Ref: 373

22) The NOT EXISTS keyword will be true if any row in the subquery fails to meet the condition. Answer: FALSE
Diff: 2 Page Ref: 372

23) A double nested set of NOT EXISTS SELECT statements can be used to find rows that meet some specified condition for every row in a table. Answer: TRUE
Diff: 3 Page Ref: 372

24) When using a double nested set of NOT EXISTS SELECT statements, a row that does not match any row matches every row. Answer: TRUE
Diff: 3 Page Ref: 372...
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