An Introduction to Database Systems 8Ed - C J Date - Solutions Manual Episode 1 Part 1 pot

Date page fm.2 General Remarks The purpose of this manual is to give guidance on how to use the eighth edition of the book An Introduction to Database Systems──referred to throughout t

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║ Eighth Edition ║

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Copyright (c) 2003 C J Date page fm.2

General Remarks

The purpose of this manual is to give guidance on how to use the

eighth edition of the book An Introduction to Database

Systems──referred to throughout the manual as simply "the book,"

or "this book," or "the present book," or just "the eighth

edition"──as a basis for teaching a database course The book is suitable for a primary (one- or two-semester) course at the junior

or senior undergraduate or first-year graduate level; it also

contains some more forward-looking and research-oriented material that would be relevant to a more advanced course Students are expected to have a basic understanding of (a) the storage and file management capabilities (indexing, hashing, etc.) of a modern

computer system, and (b) the features of a typical high-level

programming language (Java, Pascal, C, PL/I, etc.)

Let me immediately say a little more regarding these two

prerequisites:

1 In connection with the first, please note that although the book proper contains nothing on the subject, there's an online appendix available──Appendix D, "Storage Structures and Access Methods──that does provide a tutorial overview of such

matters That appendix is an upgraded version of material

that was included in the book proper in the first six

editions But file management isn't specific to database

systems; what's more, it's a huge subject in its own right,

and it has textbooks of its own──see, e.g., File Organization for Database Design, by Gio Wiederhold, published by McGraw-Hill in 1987 (which, despite the title, is really about files, not databases) That's why I've dropped the inline coverage

of such material from the last two editions of the present book

2 In connection with the second, please note that the book uses

a hypothetical language called Tutorial D as a basis for

examples throughout Tutorial D might be characterized,

loosely, as a Pascal-like language; it's defined in detail in reference [3.3] (See the subsection immediately following for an explanation of this reference format I'll have more

to say regarding reference [3.3] in particular later in these

introductory notes──see the subsection on The Third Manifesto,

pages 6-8.)

All of that being said, I want to say too that I don't think either of these prerequisites is particularly demanding; but you should be prepared, as an instructor, to sidetrack occasionally

and give a brief explanation of (e.g.) what indexes are all about,

if the question arises

A note on style: The book itself follows convention in being written in the first person plural (we, our, etc.) This manual,

by contrast, is written in the first person singular (I, my,

etc.)──except where (a) it quotes directly from the book, or (b)

it reflects ideas, opinions, positions, etc., that are due to both

Hugh Darwen and myself (again, see the subsection on The Third Manifesto, pages 6-8) The latter case applies particularly to Chapter 20 on type inheritance, Chapter 23 on temporal databases, and Chapter 26 on object/relational databases

The manual is also a little chattier than the book, using

elisions such as "it's" and "they're" instead of the more stilted

"it is" and "they are," etc

Structure of the Book

The book overall consists of a preface plus 27 chapters (divided into six parts), together with four appendixes, as follows:

Part I : Preliminaries

1 An Overview of Database Management

2 Database System Architecture

3 An Introduction to Relational Databases

4 An Introduction to SQL

Part II : The Relational Model

5 Types

6 Relations

7 Relational Algebra

8 Relational Calculus

9 Integrity

10 Views

Part III : Database Design

11 Functional Dependencies

12 Further Normalization I: 1NF, 2NF, 3NF, BCNF

13 Further Normalization II: Higher Normal Forms

14 Semantic Modeling

Part IV : Transaction Management

15 Recovery

16 Concurrency

Copyright (c) 2003 C J Date page fm.4

Part V : Further Topics

17 Security

18 Optimization

19 Missing Information

20 Type Inheritance

21 Distributed Databases

22 Decision Support

23 Temporal Databases

24 Logic-Based Databases

Part VI : Objects, Relations, and XML

25 Object Databases

26 Object/Relational Databases

27 The World Wide Web and XML

Appendixes

A The TransRelationaltm Model

B SQL Expressions

C Abbreviations, Acronyms, and Symbols

D Storage Structures and Access Methods (online only)

The preface gives more specifics regarding the contents of each part, chapter, etc It also summarizes the major differences

between this eighth edition and its immediate predecessor

By the way, if you're familiar with earlier editions, I'd like

to stress the point that this edition, like each of its

predecessors, is in large degree a brand new book──not least

because (of course) I keep learning myself and improving my own understanding, and producing a new edition allows me to correct past mistakes (In this connection, I'd like to draw your

attention to the wonderful quote from Bertrand Russell in the

book's preface Also please note the epigraphs by George

Santayana and Maurice Wilkes! It would be nice if the computer science community would take these remarks to heart.)

The following notes, also from the book's preface, are lightly edited here:

(Begin quote)

The book overall is meant to be read in sequence more or less as written, but you can skip later chapters, and later sections

within chapters, if you choose A suggested plan for a first

reading would be:

• Read Chapters 1 and 2 "once over lightly."

• Read Chapters 3 and 4 very carefully

• Read Chapters 5, 6, 7, 9, and 10 carefully, but skip Chapter 8──except, probably, for Section 8.6 on SQL (in fact, you

might want to treat portions of Section 8.6 "early," perhaps along with the discussion of embedded SQL in Chapter 4)

Note: It would be possible to skip or skim Chapter 5, too, but if you do you'll need to come back and deal with it

properly before you cover Chapter 20 or Chapters 25-27

• Read Chapter 11 "once over lightly."

• Read Chapters 12 and 14 carefully, but skip Chapter 13 (You could also read Chapter 14 earlier if you like, possibly right after Chapter 4 Many instructors like to treat the

entity/relationship material much earlier than I do For that reason I've tried to make Chapter 14 more or less

self-contained, so that it can be read "early" if you like.)

• Read Chapters 15 and 16 carefully

• Read subsequent chapters selectively (but in sequence),

according to taste and interest

I'd like to add that instructors, at least, should read the

preface too (most people don't!)

Each chapter opens with an introduction and closes with a

summary; each chapter also includes a set of exercises (and the online answers often give additional information about the subject

at hand) Each chapter also includes a set of references, many of them annotated This structure allows the subject matter to be treated in a multi-level fashion, with the most important concepts and results being presented inline in the main body of the text and various subsidiary issues and more complex aspects being

deferred to the exercises, or answers, or reference annotation, as appropriate

With regard to those references, by the way, I should explain that references are identified in the text by two-part numbers in square brackets For example, the reference "[3.1]" refers to the first item in the list of references at the end of Chapter 3:

namely, a paper by E F Codd published in CACM 25, No 2, in

February, 1982 (For an explanation of abbreviations used in

references──e.g., "CACM"──see Appendix B Regarding Codd in

particular, let me draw your attention to the dedication in this new edition of the book It's a sad comment on the state of our field that I often encounter database students or professionals who have never heard of Ted Codd.)

Copyright (c) 2003 C J Date page fm.6

(End quote)

This manual gives more specific guidance, with rationale, on what can safely be skipped and what really ought not to be As indicated above, it also gives answers to the exercises──or most

of them, at any rate; note, however, that some exercises don't have any single "right" answer, but instead are intended to

promote group discussion and perhaps serve as some kind of

miniproject Such cases are flagged in this manual by the phrase

No answer provided Note: The book also includes a number of

inline exercises embedded in the body of the text, and the remarks

of this paragraph apply to those inline exercises too

Structure of this Manual

The broad structure of this manual mirrors that of the book

itself: It consists of this preface, together with notes on each part, each chapter, and each appendix from the subject book

(including the online Appendix D) Among other things, the notes

on a given part or chapter or appendix:

• Spell out what that piece of the book is trying to achieve

• Explain the place of that piece in the overall scheme of

things

• Describe and hit the highlights from the relevant text

• Indicate which items can be omitted if desired and which must definitely not be

• Include additional answers to exercises (as already noted) and, more generally, give what I hope are helpful hints regarding the teaching of the material

The Third Manifesto

You might be aware that, along with my colleague Hugh Darwen, I

published another database book a little while back called The Third Manifesto [3.3].* The Third Manifesto consists of a

detailed technical proposal for the future of data and database systems; not surprisingly, therefore, the ideas contained therein

inform the present book throughout Which isn't to say The Third Manifesto is a prerequisite to the present book──it isn't; but it

is directly relevant to much that's in this book, and further

pertinent information is often to be found there Instructors in

particular really ought to have a copy available, if only for

reference purposes (I realize this recommendation is somewhat self-serving, but I make it in good faith.) Students, on the

other hand──at least beginning students──would probably find much

of The Third Manifesto pretty heavy going It's more of a

graduate text, not an undergraduate one

──────────

* The full title is Foundation for Future Database Systems: The Third Manifesto (2nd edition, Addison-Wesley, 2000) The first

edition (1998) had the slightly different title Foundation for Object/Relational Databases: The Third Manifesto; however, it

wasn't exclusively about object/relational databases as such,

which was why we changed the title for the second edition By the

way, there's a website, too: http://www.thethirdmanifesto.com The website http://www.dbdebunk.com also contains much relevant

material

──────────

I should explain why we called that book The Third Manifesto

The reason is that there were two previous ones:

• The Object-Oriented Database System Manifesto [20.2,25.1]

• The Third Generation Database System Manifesto [26.44]

Like our own Manifesto, each of these documents proposes a basis

for future DBMSs However:

• The first essentially ignores the relational model! In our opinion, this flaw is more than enough to rule it out

immediately as a serious contender

• The second does agree that the relational model mustn't be ignored──but unfortunately goes on to say that supporting the

relational model means supporting SQL

The Third Manifesto, by contrast, takes the position that any

attempt to move forward, if it's to stand the test of time, must reject SQL unequivocally (see the next subsection, "Some Remarks

on SQL," for further elaboration of this point) Of course, we're not so stupid as to think SQL is going to go away; after all,

COBOL has never gone away Au contraire, SQL databases and SQL

applications are obviously going to be with us for a long time to come So we do have to worry about what to do about today's "SQL

legacy," and The Third Manifesto does include some specific

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suggestions in this regard Further discussion of those

suggestions would be out of place here, however

The Third Manifesto also discusses and stresses several

important logical differences (the term is due to

Wittgenstein)──i.e., differences that are quite simple, yet

crucial, and ones that many people (not to mention products!) seem

to get confused over Some of the differences in question are:

• Model vs implementation

• Value vs variable

• Type vs representation

• Read-only operator vs update operator

• Argument vs parameter

• Type vs relation

and so on (this isn't meant to be an exhaustive list) These

notes aren't the place to spell out exactly what all of the

differences are (in any case, anyone who claims to be an

instructor in this field should be thoroughly familiar with them already); rather, my purpose in mentioning them here is to alert you to the fact that they are appealed to numerous times

throughout the book, and also to suggest that you might want to be

on the lookout for confusion over them among your students Of

course, the various differences are all explained in detail in The Third Manifesto, as well as in the book itself

As noted earlier, The Third Manifesto also includes a

definition of Tutorial D──although, to be frank, there shouldn't

be any need to refer to that definition in the context of the

present book (the Tutorial D examples should all be pretty much

self-explanatory)

Some Remarks on SQL

As noted in the previous subsection, The Third Manifesto takes the

position that any attempt to move forward, if it's to stand the

test of time, must reject SQL This rather heretical position

clearly needs some defending; after all, earlier editions of An Introduction to Database Systems actually used SQL to illustrate relational ideas, in the belief that it's easier on the student to show the concrete before the abstract Unfortunately, however, the gulf between SQL and the relational model has now grown so

wide that I feel it would be actively misleading to continue to use it for such a purpose Indeed, we're talking here about

another huge logical difference: SQL and the relational model

aren't the same thing!──and in my opinion it's categorically not a

good idea (any more) to use SQL as a vehicle for teaching

relational concepts Note: I make this observation in full

knowledge of the fact that many database texts and courses do

exactly what I'm here saying they shouldn't

At the risk of beating a dead horse, I'd like to add that SQL today is, sadly, so far from being a true embodiment of relational principles──it suffers from so many sins of both omission and

commission (see, e.g., references [4.15-4.20] and [4.22])──that my own preference would have been to relegate it to an appendix, or even to drop it entirely However, SQL is so important from a commercial point of view (and every database professional does need to have some familiarity with it) that it really wouldn't have been appropriate to dismiss it in so cavalier a fashion I've therefore settled on a compromise: a chapter on SQL basics in Part I of the book (Chapter 4), and individual sections in later chapters describing those aspects of SQL, if any, that are

relevant to the subject of the chapter in question (You can get some idea of the extent of that SQL coverage from the fact that there are "SQL Facilities" sections in 14 out of a total of 23 subsequent chapters.)

The net result of the foregoing is that, while the eighth

edition does in fact discuss all of the most important aspects of SQL, the language overall is treated as a kind of second-class citizen And while I feel this treatment is appropriate for a book of the kind the eighth edition is meant to be, I do recognize that some students need more emphasis on SQL specifically For such students, I believe the book provides the basics──not to

mention the proper solid theoretical foundation──but instructors will probably need to provide additional examples etc of their own to supplement what's in the book (In this connection, I'd like, somewhat immodestly, to recommend reference [4.20] as a good resource.)

What Makes this Book Different?

The following remarks are also taken from the book's preface, but again are lightly edited here:

(Begin quote)

Every database book on the market has its own individual strengths and weaknesses, and every writer has his or her own particular ax

to grind One concentrates on transaction management issues;

another stresses entity/relationship modeling; another looks at

Copyright (c) 2003 C J Date page

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everything through a SQL lens; yet another takes a pure "object" point of view; still another views the field exclusively in terms

of commercial products; and so on And, of course, I'm no

exception to this rule──I too have an ax to grind: what might be

called the foundation ax I believe very firmly that we must get

the foundation right, and understand it properly, before we try to build on that foundation This belief on my part explains the heavy emphasis in this book on the relational model; in

particular, it explains the length of Part II──the most important part of the book──where I present my own understanding of the

relational model as carefully as I can I'm interested in

foundations, not fads and fashions Products change all the time, but principles endure

In this regard, I'd like to draw your attention to the fact that there are several important "foundation" topics for which this book, virtually alone among the competition, includes an

entire in-depth chapter (or an appendix, in one case) The topics

in question include:

• Types

• Integrity

• Views

• Missing information

• Inheritance

• Temporal databases

• The TransRelational Model

In connection with that same point (the importance of

foundations), I have to admit that the overall tone of the book has changed over the years The first few editions were mostly descriptive in nature; they described the field as it actually was

in practice, "warts and all." Later editions, by contrast, were

much more prescriptive; they talked about the way the field ought

to be and the way it ought to develop in the future, if we did things right And the eighth edition is certainly prescriptive in this sense (in other words, it's a text with an attitude!) Since the first part of that "doing things right" is surely educating oneself as to what those right things actually are, I hope this new edition can help in that endeavor

(End quote)

The foregoing remarks explain (among other things) the

comparative lack of emphasis on SQL Of course, it's true that students who learn the theory thoroughly first are going to have a few unpleasant surprises in store if and when they get out into the commercial world and have to deal with SQL products; it's also