The World Wide Web has been credited with br ing ing the Internet to the masses. The Internet was previously the stomp ing ground of academics and a small, elite group of computer professionals, mostly UNIX programmers and other od db all types, runn ing obscure commands like ftp and f ing er, archie and telnet, and so on. With the arrival of graphical browsers for the Web, the Internet suddenly exploded. Anyone could find th ing s on the Web. You didn't need to be "in the know" anymore--you just needed to be properly networked. Equipped with Netscape Navigator or Internet Explorer or any other browser, everyone can now explore the Internet freely. But graphical browsers can be limit ing . The very interactivity that makes them the ideal interface for the Internet also makes them cumbersome when you want to automate a task. It's analogous to edit ing a document by hand when you'd like to write a script to do the work for you. Graphical browsers require you to navigate the Web manually. In an effort to diminish the amount of tedious point ing -and- click ing you do with your browser, this book shows you how to liberate yourself from the confines of your browser. Web Client Programm ing with Perl is a behind-the-scenes look at how your web browser interacts with web servers. Readers of this book will learn how the Web works and how to write software that is more flexible, dynamic, and powerful than the typical web browser. The goal here is not to rewrite the browser, but to give you the ability to retrieve, manipulate, and redistribute web-ba sed information in an automated fashion. Who This Book Is For I like to think that this book is for everyone. But since that's a bit of an exaggeration, let's try to identify who might really enjoy this book. This book is for software developers who want to expand into a new market niche. It provides proof-of-concept examples and a compilation of web-related technical data. This book is for web administrators who maintain large amounts of data. Administrators can replace manual maintenance tasks with web robots to detect and correct problems with web sites. Robots perform tasks more accurately and quickly than human hands. But to be honest, the audience that's closest to my heart is that of computer enthusiasts, tinkerers, and motivated students, who can use this book to satisfy their curiosity about how the Web works and how to make it work for them. My editor often talks about when she first learned UNIX script ing and how it opened a world of automation for her. When you learn how to write scripts, you realize that there's very little that you can't do within that universe. With this book, you can extend that confidence to the Web. If this book is successful, then for almost any web-related task you'll find yourself think ing , "Hey, I could write a script to do that!" Unfortunately, we can't teach you everyth ing . There are a few th ing s that we assume that you are already familiar with: G The concept of client/server network applications and TCP/IP. G How the Internet works, and how to access it. G The Perl language. Perl was chosen as the language for examples in this book due to its ability to hide complexity. Instead of deal ing with C's data structures and low-level system calls, Perl introduces higher-level functions and a straightforward way of defin ing and us ing data. If you aren't already familiar with Perl, I recommend Learn ing Perl by Randal Schwartz, and Programm ing Perl (popularly known as "The Camel Book") by Larry Wall, Tom Christiansen, and Randal Schwartz. Both of these books are published by O'Reilly & Associates, Inc. There are other fine Perl books as well. Check out http://www.perl.com for the latest book critiques. Is This Book for You? Some of you already know why you picked up this book. But others may just have a nagg ing feel ing that it's someth ing useful to know, though you may not be entirely sure why. At the risk of seem ing self-serv ing , let me suggest some ways in which this book may be helpful: G Some people just like to know how th ing s tick. If you like to think the Web is magic, fine--but there are many who don't like to get into a car without know ing what's under the hood. For those of you who desire a better technical understand ing of the Web, this book demystifies the web protocol and the browser/server interaction. G Some people hate to waste even a minute of time. Given the choice between repeat ing an action over and over for an hour, or writ ing a script to automate it, these people will choose the script every time. Call it productivity or just stubbornness--the effect is the same. Through web automation, much time can be saved. Repetitive tasks, like track ing packages or stock prices, can be relegated to a web robot, leav ing the user free to perform more fruitful activities (like eat ing lunch). G If you understand your current web environment, you are more likely to recognize areas that can be improved. Instead of wait ing for solutions to show up in the marketplace, you can take an active role in shap ing the future direction of your own web technology. You can develop your own specialized solutions to fit specific problems. G In today's frenzied high-tech world, knowledge isn't just power, it's money. A reasonable understand ing of HTTP looks nice on the resume when you're compet ing for software contracts, consult ing work, and jobs.

a simple script to pop up a small window like element upon click ing on the label Klick and closes when use click s on Close (title of the window) it is basically <div> element

①：这种情况一般是因为你在数据库中没有这个数据库，你新建一个你要导入的数据库名字的数据库，然后选中该数据库，再进行导入基本上就可以了 ②：初学者在建立表时容易遇到这样的报错： Error Code : 1046 . No database selected Select the default DB to be u sed by double - click ing its name in the SCHEMAS list in the sidebar. 其实就是未指定数据库， 在 MySql 中建立数据库后create

MySQL workbench 导入表格，查询时 Error Code : 1046 . No database selected Select the default DB to be u sed by double - click ing its name in the SCHEMAS list in the sidebar. 输入use +要用的schemas名 在workbench中操作删除了某选中数据库， 点击左上角第一个那个“+SQL”（create a new sql tab for execut ing queries ） 打开.sql文件或者粘贴sql语句并执行 报错： Error Code : 1046 . No database selected Select the default DB to be u sed by double - click ing its name in the SCHEMAS list in the sidebar.