Apress the definitive guide to MySQL 2nd edition oct 2003 ISBN 1590591445

The Definitive Guide to MySQL, Second EditionApress © 2004 824 pages Provides a thorough introduction to the installation, configuration, implementation, and administration of MySQL... W

The Definitive Guide to MySQL, Second Edition

Apress © 2004 (824 pages)

Provides a thorough introduction to the installation, configuration, implementation, and administration of MySQL.

The Definitive Guide to MySQL, Second Edition, is the

perfect all-in-one guide to MySQL Whether you’re new

to Web application development or you’re already an experienced database analyst, this book describes all

of the facets of MySQL configuration, administration, and database application development Greatly

expanded from its widely-praised first edition, this

updated revision provides additional information about MySQL tools such as MySQL Control Center and

the author of Definitive Guide to Excel VBA, Second Edition, published by Apress.

Michael Kofler

Translated by David Kramer

The Definitive Guide to MySQL, Second Edition Copyright © 2004 byMichael Kofler

All rights reserved No part of this work may be reproduced or transmitted

in any form or by any means, electronic or mechanical, including

photocopying, recording, or by any information storage or retrieval

system, without the prior written permission of the copyright owner andthe publisher

ISBN (pbk): 1-59059-144-5

Trademarked names may appear in this book Rather than use a

trademark symbol with every occurrence of a trademarked name, we usethe names only in an editorial fashion and to the benefit of the trademarkowner, with no intention of infringement of the trademark

The information in this book is distributed on an "as is" basis, withoutwarranty Although every precaution has been taken in the preparation ofthis work, neither the author nor Apress shall have any liability to anyperson or entity with respect to any loss or damage caused or alleged to

be caused directly or indirectly by the information contained in this work.The source code for this book is available to readers at

http://www.apress.com, in the Downloads section You will need toanswer questions pertaining to this book in order to successfully

download the code

About the Author

Kofler is also the author of Definitive Guide to Excel VBA, Second

Edition, published by Apress.

About the Translator

DAVID KRAMER EARNED HIS PH.D in mathematics at the University ofMaryland, and his M.A in music at Smith College For many years heworked in academia, first as a professor of mathematics and computerscience, and later as a director of academic computing Over the pasteight years he has edited hundreds of books in mathematics and thesciences, and has translated a number of books in a variety of fields,

including Definitive Guide to Excel VBA, by Michael Kofler; Enterprise JavaBeans 2.1, by Stefan Denninger and Ingo Peters; and Cryptography

in C and C++, by Michael Welschenbach, all published by Apress Other translations include The Game's Afoot! Game Theory in Myth and

Paradox, by Alexander Mehlmann; the children's musical Red Riding! Red Riding!, by Ernst Ekker with music by Sergei Dreznin; In Quest of Tomorrow's Medicines, by Jürgen Drews; and the novel To Err Is Divine,

by Ágota Bozai, which will be published by Counterpoint Press in April2004

MySQL is available for many applications free of charge (GPLlicense)

Since the licensing restrictions of GPL are unacceptable for manycommercial applications, there are reasonably priced commerciallicenses and optional support contracts

MySQL is on the verge of repeating in the database market thesuccess achieved by Linux in the operating system sector Incombination with PHP or Perl, MySQL is providing the databasesystem for more and more web sites (A favorite combination isLinux + Apache + MySQL + Perl or PHP Such systems are called

"LAMP systems" for short.) MySQL is not just for small web sites;

it is used by large firms with huge amounts of data, such as

Yahoo!, Slashdot, and Google

This book provides a complete application- and example-oriented

introduction to the database system MySQL No previous knowledge,either of SQL or database design, is assumed

The introductory Part I of the book begins with an extensive introduction

on installation under Windows and Linux We also consider the

installation of components that are used in combination with MySQL

(Apache, PHP, phpMyAdmin, Perl, Connector/MyODBC) Building onthis, our first example will show the basic use of MySQL and PHP

Part II, "Fundamentals," provides a large amount of background material

on the use of various user interfaces, on the database language SQL, onthe proper design of databases, on the use of InnoDB tables, on the

access system of MySQL, and on many other topics on administration(such as backups, logging, and replication)

In Part III, "Programming," we emphasize the language PHP: Three

chapters cover basic techniques of programming and show how to

construct two extensive examples (bookkeeping, a discussion forum).Most of the PHP examples can be tried out live on my web site We dealwith other programming languages, too, with chapters devoted to Perl,Java, C/C++, and VB/VB.NET/C#

We end the main text with a reference section (Part IV) that provides anoverview of the SQL commands of MySQL, the commands and options

of the administrative tools, and the functions of important programminginterfaces (PHP, Perl, C, Java)

Finally, there are several appendices, comprising (A) a glossary of terms,(B) breaking news on the forthcoming MySQL version 4.1, (C) information

on the example files for this book (available at www.apress.com), and(D) a bibliography with suggestions for further reading

In combination with the example databases and programs, this book

should provide a good foundation for the development of your own

database applications In this I wish you much fun and success Michael Kofler, August 2003 <mysql@kofler.cc> http://www.kofler.cc/mysql

There is much that is new This book has been completely revised, fromthe first page to the last (It took as long to produce this second edition as

to write the first edition from scratch!) The following list indicates the mostimportant changes:

MySQL: The book now covers MySQL 4.0 and to some extent

MySQL 4.1 These changes appear throughout the entire book,from installation to the reference section to the appendixes

MySQL 4.0 and 4.1? How can a full-text search be accomplishedefficiently?

establishing connections

Administration: Everything related to administration is contained

in a single clearly structured chapter New sections deal with theadministration of InnoDB tables and server tuning (including

Query Cache)

PHP: All PHP examples have been reworked in PHP 4.3 The

HTML code generated from the PHP examples is now largely

development of ADO.NET applications with the programminglanguages VB.NET and C#

Reference: The three reference chapters have been thoroughly

brought up to date and expanded with new sections (C functions,JDBC classes)

MySQL 4.1: Appendix B brings together all known changes inMySQL 4.1: improved character set support (including Unicode),

the use of subSELECTs, the management of geometric and

geographic data (GIS), the use of precompiled commands

(prepared statements), etc.

Several chapters in this book deal with the programming of MySQLapplications in a variety of programming languages, such as PHP, Perl,

C, C++, Java, and Visual Basic These chapters assume that the reader

is familiar with the specific programming language (There is simply noroom in this book to offer an introduction to a number of programminglanguages.) In other words, you will profit from, say, the PHP chapter inthis book only if you are already familiar with the programming languagePHP

To the extent that we are dealing with web applications, almost all of theapplications in this book can be tried out directly on my website

(www.kofler.cc) The source code for all the examples is available atwww.apress.com in the downloads section

In the longer program listings in this book you will find at the beginning ofthe example a comment line that specifies the file name appearing in theexample files on the web site, for example,

<! php-programming/simpleinput.php >

To save space, sometimes only the most interesting passages in theprogram code are printed

The functionality of MySQL and of the programs, programming

languages, and libraries placed in its environment changes with everynew version—which sometimes appear weekly The following overviewindicates which versions I have worked with (explanations of the variousnames will appear at appropriate places in the book):

MySQL: Version 4.0.14 In most of the example programs,

however, compatibility with MySQL 3.23.n was taken into

account, since this version is still in use by many Internet serviceproviders On the other hand, the latest developments of MySQL4.1 were tested with a development version (alpha version, fromend of July 2003), as described in Appendix B

Visual Basic, VBA, ADO: Visual Basic programs were

developed and tested with VB6 and VBA6 and ADO versions 2.1and 2.7

SQL commands and functions, as well as methods, classes, and keywords in SQL, C, Java, PHP, Perl, VB, etc., generally appear in italic

(e.g., SELECT, mysql_query) (Note, however, that when the background

text is italic, as in the gray "Remark," "Tip," "Caution," and "Pointer"

boxes and some section headings, such commands and functions will appear in a roman font; e.g., SELECT.)

Unix/Linux user names also appear in italic (e.g., root, mysql).

MENU COMMANDS USE CAPS AND SMALL CAPS (e.g., FILE |OPEN)

MySQL options and configuration parameters appear in regularroman type (e.g., default-charset)

observe the following conventions:

\Windows\means the Windows directory (e.g., C:\Windows or

Programs\means the directory under Windows for programinstallation (e.g., C:\Programs or D:\Program Files).Mysql\means the MySQL installation directory (e.g., C:\Mysql

or D:\Program Files\Mysql)

Many commands will be presented in this book We will be moving backand forth between the Unix/Linux and Windows conventions The

following two commands are equivalent:

root# mysqladmin -u root -h localhost password xxx

> mysqladmin -u root -h localhost password xxx

In each case we have given the system prompt (root# for Unix/Linuxand > for Windows) You type in only what follows the prompt (here in

boldface type) Under Unix/Linux it is possible to divide long inputs over

several lines The lines are separated by means of the backslash symbol

\ We shall often use this convention in this book The following commandthus corresponds to the command above:

I have attempted in this book to make as little use of abbreviations aspossible However, there are several abbreviations that will be usedrepeatedly without being introduced anew in each chapter:

VBA the Microsoft Office package)

Part I: Introduction

Chapter 1: What Is MySQL?

Chapter 2: The Test Environment

Chapter 3: Introductory Example (An Opinion Poll)

Chapter 1: What Is MySQL?

This chapter begins with an overview of the most important conceptsfrom the world of databases and then delves into the possibilities andlimitations of MySQL What is MySQL? What can it do, and what is itunable to do?

In addition to describing the central functions of MySQL, we shall alsodiscuss fully the issue of licensing MySQL When is one permitted to useMySQL without payment, and when is a license required?

Before we can answer the central question of this chapter, namely, What

is MySQL? you and I must find a common language Therefore, this

section presents a rudimentary database glossary, without going intogreat detail (If you have already had significant dealings with relationaldatabases, you can skip the next couple of pages in good conscience.)

There is scarcely to be found a term that is less precise than database A

database can be a list of addresses residing in a spreadsheet program(such as Excel), or it can be the administration files of a

telecommunications firm in which several million calls are registereddaily, their charges accurately calculated, monthly bills computed, andwarning letters sent to those who are in arrears A simple database can

be a stand-alone operation (residing locally on a computer for a singleuser), while others may be used simultaneously by thousands of users,with the data parceled out among several computers and dozens of harddrives The size of a database can range from a few kilobytes into theterabytes.[1]

In ordinary usage, the word "database" is used to refer to the actual data,the resulting database files, the database system (such as MySQL orOracle), or a database client (such as a PHP script or a program written

in C++) Thus there arises a great potential for confusion as soon as twopeople begin to converse on the subject of databases

Relations, Database Systems, Servers, and Clients

A database is an ordered collection of data, which is normally stored in one or more associated files The data are structured as tables, where

cross references among tables are possible The existence of such

relations among the tables leads to the database being called a relational database.

Let us clarify matters with an example A database might consist of atable with data on a firm's customers (name, address, etc.), a table withdata on the products the firm offers, and finally, a table containing the

in the other two tables (for example, via customer and product numbers).MySQL, Oracle, the Microsoft SQL server, and IBM DB2 are examples of

relational database systems Such a system includes the programs for

managing relational databases Among the tasks of a relational databasesystem are not only the secure storage of data, but also such jobs as theprocessing of commands for querying, analyzing, and sorting existingdata and for storing new data All of this should be able to take place notonly on a single computer, but over a network as well Instead of a

database system we shall often speak of a database server.

Where there are servers, there are clients Every program that is

connected to the database system is called a database client Database

clients have the job of simplifying the use of the database for the enduser No user of a database system in his or her right mind would wish tocommunicate directly with the database server That is much too abstractand inconvenient (Let programmers worry about such direct

communication!) Instead, the user has a right to expect convenient

tables, listboxes, and so on to enable the location of data or to input newdata

Database clients can assume a variety of forms, and indeed, they areoften not recognized by the user as database programs at all Someexamples of this type of client are HTML pages for the display and input

of messages in an on-line discussion group, a traditional program withseveral windows for managing addresses and appointments, and a Perlscript for executing administrative tasks There is thus wide scope fordatabase programming

Relational Versus Object-Oriented Database Systems

Relational databases have dominated the database world for decades,and they are particularly well suited for business data, which usually lendthemselves to structuring in the form of tables Except for the followingtwo paragraphs, this entire book discusses only relational databases(though we shall not always stress this point)

databases can store free-standing objects (without having to arrangethem in tables) Although in recent years there has been a trend in thedirection of object-oriented programming languages (such as Object-Store, O2, Caché), object-oriented databases have found only a smallmarket niche

Note that relational databases can be accessed by means of object-oriented programming languages However, that does not turn a

relational database into an object-oriented one Object-oriented databasesystems enable direct access to objects defined in the programming

language in question and the storage of such objects in the databasewithout conversion (persistency) It is precisely this that is not possiblewith relational database systems, in which everything must be structured

modified) However, for efficient use of the data it is necessary that from

To create such a list, one formulates queries The result of the query is

again a table; however, it is one that exists in active memory (RAM) andnot on the hard drive

To formulate a query one uses SQL instructions, which are commands forselecting and extracting data The abbreviation SQL stands for

Structured Query Language, which has become a standard in the

formulation of database queries Needless to say, every producer of adatabase system offers certain extensions to this standard, which dilutesthe goal of compatibility among various database systems

necessary for the database file, and second, the index must be updatedeach time the data are altered, and this costs time (Thus an index savestime in the reading of data, but it costs time in entering and altering data

It thus depends on the use to which the data are to be put whether anindex is on the whole a net plus or minus in the quest for efficiency.)

A special case of an index is a primary index,or primary key,which is

distinguished in that the primary index must ensure a unique reference to

a record Often, for this purpose one simply uses a running index number(ID number) Primary indexes play a significant role in relational

databases, and they can speed up access to data considerably

[1]It all started with the megabyte, which is about one million bytes Aterabyte is 1024 gigabytes, which in turn is approximately one thousand

"large," while "giga-" is derived from the Greek word for "giant." In turn,

"tera-" is from the Greek word for "monster." It would appear that

numbers once regarded as large, gigantic, or even monstrously hugehave become part of our everyday vocabulary

MySQL is a relational database system If you can believe many diehardMySQL fans, MySQL is faster, more reliable, and cheaper—or, simplyput, better—than any other database system (including commercial

systems such as Oracle and DB2) Many MySQL opponents continue tochallenge this viewpoint, going even so far as to assert that MySQL is noteven a relational database system We can safely say that there is alarge bandwidth of opinion

The fact is that there is an ever increasing number of MySQLusers, and the overwhelming majority of them are quite satisfiedwith MySQL Thus for these users we may say that MySQL is

http://www.hughes.com.au/

The following list shows the most important properties of MySQL Thissection is directed to the reader who already has some knowledge ofrelational databases We will use some terminology from the relationaldatabase world without defining our terms exactly On the other hand, theexplanations should make it possible for database novices to understand

is, they query data, save changes, etc The clients can run on thesame computer as the server or on another computer

SQL compatibility: MySQL supports as its database language—

as its name suggests—SQL (Structured Query Language) SQL

is a standardized language for querying and updating data andfor the administration of a database

Replication: Replication allows the contents of a database to be

copied (replicated) onto a number of computers In practice, this

is done for two reasons: to increase protection against systemfailure (so that if one computer goes down, another can be putinto service) and to improve the speed of database queries

Transactions: In the context of a database system, a transaction

means the execution of several database operations as a block.The database system ensures that either all of the operations arecorrectly executed or none of them This holds even if in the

middle of a transaction there is a power failure, the computercrashes, or some other disaster occurs Thus, for example, it

cannot occur that a sum of money is withdrawn from account A but fails to be deposited in account B due to some type of system

error Transactions also give programmers the possibility of

interrupting a series of already executed commands (a sort ofrevocation) In many situations this leads to a considerable

simplification of the programming process

In spite of popular opinion, MySQL has supported transactions for

a long time One should note here that MySQL can store tables in

a variety of formats The default table format is called MyISAM,and this format does not support transactions But there are anumber of additional formats that do support transactions Themost popular of these is InnoDB, which will be described in itsown chapter

Foreign key constraints: These are rules that ensure that there

Programming languages: There are quite a number of APIs

(application programming interfaces) and libraries for the

development of MySQL applications For client programming youcan use, among others, the languages C, C++, Java, Perl, PHP,Python, and Tcl

Platform independence: It is not only client applications that run

under a variety of operating systems; MySQL itself (that is, theserver) can be executed under a number of operating systems.The most important are Apple Macintosh OS X, Linux, MicrosoftWindows, and the countless Unix variants, such as AIX, BSDI,FreeBSD, HP-UX, OpenBSD, Net BSD, SGI Iris, and Sun Solaris

Speed: MySQL is considered a very fast database program This

speed has been backed up by a large number of benchmark

tests (though such tests—regardless of the source—should beconsidered with a good dose of skepticism)

Many of the shortcomings listed in this section can be found on the to-dolist of the team of MySQL developers, or have already been

implemented

Pointer The documentation for MySQL is not at all silent on the

subject of shortcomings or missing features There is a quitereadable section in the MySQL documentation on the topic

"How standards-compatible is MySQL?" There you will findextensive information on the points at which MySQL fails tocomply with current standards Often, a reason for theshortcoming is provided, and sometimes as well somepointers on how to get around the difficulty:

http://www.mysql.com/doc/en/Compatibility.html

Note also that all of the shortcomings mentioned here are onthe to-do list of the developers and will be alleviated in futureversions of MySQL

ANSI-SQL/92 Limitations

ANSI SQL/92 is a standardized definition of the database query languageSQL Many commercial database systems are largely compatible withthis standard and also offer many extensions

MySQL is also conspicuous for its countless extensions, but

unfortunately, the compatibility is not so extensive as is the case for otherdatabase systems The points described in greater detail in what follows

(subSELECTs, views, triggers, stored procedures) are examples of the

lack of ANSI-SQL/92 compatibility

These limitations usually make it impossible (or merely very difficult) toadapt existing databases and the associated SQL code from other

database systems into MySQL Conversely, it is almost as difficult to

transfer a MySQL solution to another database system if you have notscrupulously employed only the ANSI-SQL/92-conforming features of

MySQL (The temptation to use the useful proprietary features proves in

executed by the server during certain database operations If adatabase is incapable on its own of ensuring referential integrity,then it is usually triggers that are brought into play to assist inthis For example, a trigger can be executed every time a record

is to be deleted, which would test whether this operation is

permissible and prohibit the action if need be

The lack of subSELECTs, views, SPs, and triggers does not greatly

restrict the possibilities open to client programmers, but it does lead to asituation in which the program logic is transferred from the server level tothe client level The result is more complex or expensive client

programming than would otherwise be the case, leading to redundancies

in code and problems with maintenance and alteration of code

Further Limitations

The following limitations actually have nothing to do with ANSI-SQL/92but nonetheless play a significant role in practice

MySQL 4.0 supports a variety of character sets and the

associated sort orders, but at present can have only a single sort order active at a time If the sort order must be changed, MySQL

MySQL 4.0 is unable to deal with Unicode or other mutibyte

character strings (Of course, it is possible to treat such data asbinary objects, but there are no functions for dealing with

character strings, in particular, no usable sorting or comparisonalgorithms.) This limitation, too, has been removed in version 4.1

Even for connoisseurs of MySQL it is a bit of a challenge to keep track ofwhich version of MySQL is current and which functions are contained inwhich versions This section provides some information on MySQL

numbering

As of March 2002 there are four main versions being worked on by theMySQL development team:

when MySQL 4.1.n will be at a point where it can be

recommended for production use, probably not before 2004

MySQL 5.0.n: The first published version in this series is

expected in 2004 It is completely open as to when the first stable

process and that new functions and even incompatible changesare to be expected Although an alpha version is not publisheduntil it contains no known errors, it is highly probable that manyundiscovered errors still lurk within Loss of data during testing of

Production means that the MySQL development community has

the impression that the version is mature and stable enough that

it can be used for mission-critical purposes

According to the MySQL documentation, in production versions, onlycorrections, and no new functionality, are to be expected However, thishas not always held true in the past Of particular note is the case of

MySQL 3.23.n After the version had been declared stable (3.23.32),

there came general support for InnoDB and BDB tables (3.23.34), andlater, integrity rules for InnoDB tables (3.23.44) Furthermore, many minorextensions were introduced As a rule, MySQL developers are pleasedwith such extensions, but at the same time, compatibility problems

among different production versions can arise

In practice, this means that a new MySQL version (that is, n.n.0) always

kind In the past, it frequently occurred that particular functions became