1 comments about SQL Power!: The Comprehensive Guide (Power!).

1. SQL Power!: The Comprehensive Guide (Power!)
   Thanks for a well-written book with REAL LEARNING in mind. I despise those books that have the students follow graphical step-by-steps and step through a tutorial. This book forces the students to READ! the text. This is what I like for my students because I think it forces them to learn. They learn not only how to do something, but why they do it that way. This book is A-1!!!

5 comments about Sams Teach Yourself MySQL in 21 Days.

1. What this book is and what this book is not?
   This is not a book neither mysql, nor sql language, nor database management.
   Examples are left unexplained, some critical topics are left uncovered, others are left to author's intuition, chapters are bad organized, there is a sense of non-logical organization all over the book. If this is your first book about mysql, you will "teach yourself" nothing about mysql. If not, you simply don't need this book. I suggest to spend money for this book to buy an ink cartridge and some paper to print out the official mysql manual. This book has definitively no mean.



2. Typos galore

   I know I'm throwing fuel on a bonfire, but this book [stinks]!

   HUNDREDS of errors and misinformation. I tried to return the book but found out if I open the CD it is non-returnable.

   The only reason I opened the CD was to get a file that WASN'T EVEN ON THE CD!

   Next time I will read the reviews on Amazon first.




3. I thought that this book would teach me the basics of MySQL in a relatively short time. While I did learn some things, I spent most of my time figuring out how the author got from one step to the next. There were numerous typos in the code that left me, as a beginner, scratching my head. Most SAMS books are great, but not this one.



4. This book doesnt waste time with all the little details and just talks about the major points. Want to be a MySQL guru? Then this books is NOT for you.
   However, if you are know how to code and how to use flat files then this book is for you and will teach you how to code your scripts with the use of MySQL database.
   Yes there are some typos like others pointed out but who uses the codes word for word from the book? You should know the basics of scripting language like Perl or PHP before buying this book. And you might want to buy a book about SQL.
   This book isn't here to teach you Perl, PHP or SQL so making small errors in those codes shouldn't affect your buying decision.
   This book teaches MySQL database nice and simply and I still use it as a referrence after 2 years of working with MySQL.



5. Two thirds of the book are about nothing. If the book was completed only on 100 or 150 pages ("the best of"), i could give 3 stars..

   It is a bit chaotic ordered, there are mistakes in that book and author often uses magic formulas "If you need do this, do this: ...". The book is much more about How, not Why.

   If you have some experiences with programming in any language, buying subj. is only wasting money..

5 comments about JSP, Servlets, and MySQL.

1. This is the worst technical book I have ever had the misfortune to read. I was originally excited to purchase the book as the Table of Contents outlined topics I am interested in studying. However, the book is riddled with text and code errors. In fact, the author had the audacity to change the downloadable source code after the book was published. Therefore, you can't even get the code source for the examples in the book, and the new code comes with no instructions! In addition, the author does a poor job of explaining the concepts he is trying to teach. M&T Books should be ashamed for publishing this poorly edited text. I truly feel that I have been swindled by this company/author and would like a full refund. The book is so bad that I will avoid all M&T Books in the future.



2. I picked up this book because I had already decided that I was going to use JSP and MySQL together to create my web site. Quite frankly, I haven't learned anything from this book that wasn't done better in other books, which is a shame because this is an area that really deserves a more thorough treatment. In several areas he just fills several pages with code and hardly explains it at all, other than a few lines--so why bother showing the entire example? This is a clear case where better editorial review would have helped to focus the book on material that would have been more helpful to the reader.



3. This book has a very interesting title and the TOC look great too, but unfortunately the content is carelessly chosen/written. I don't want to repeat the error in the code listings. I just want to mention about design problems in this book.

   JSP has its born-with problem that it is hard to set boundary for Server Programmer and HTML Programmer. These 2 kinds of work need different skill set. That's why separation of Data and Presention is very important to JSP web site design.

   The author of this book carefully avoided to include much JSP code in HTML pages, but his design leads to another extreme: almost every control (forms, buttons, links) are generated by JSP code. This approach will create a nightmare for JSP programmers for changing the appearance of the web site.

   So besides coding error, this book has design issues. I really can't imagine who should be the audience...




4. The TOC sounded great, so I bought the book. I hate to reiterate what other reviewers have already said, but it's true: there are so many errors it's rediculous. It was painful to figure out why I wasn't understanding some of the material (for example, the SAME SQL statement produces two DIFFERENT result sets on page 208/209)when in fact it was just a very poorly edited book. The book's topics are perfect - now someone needs to go through it with a pitchfork to weed out all the errors. Not to mention that the example code you can download has been refactored (to put it nicely). It's an expensive lesson in wasted money and time and frustration, but from now on, I'll always check the reviews here before ordering any book.



5. I found this book very helpful. I knew nothing about JSP, servlets and mysql. My previous experience came from a standard university course in Java. The book took me through setting up tomcat, mysql,etc. It started me off using the technologies. The book is built around a core example. I didn't reproduce and test the code supplied but dipped in to take what I needed. Downloading the code from the website was confusing. Overall this book has been very helpful. I found the content concise and to the point. Thanks to the author.

2 comments about MySQL: Your visual blueprint for creating open source databases.

1. This book is great if you're looking to get started quickly with MySQL. I was able to set up and create a database within hours after buying the book, with only minimal prior exposure to MySQL. Plus, it's a great quick reference for some of the standard MySQL commands that you may not need to use on a super-regular basis. The majority of the teaching is done through diagrams and examples, which allows the user to see what's supposed to happen, and have a gauge of how their performing. The text is just over half of the meat of the book, and really just fills in the blank spots that the diagrams leave out. I highly recommend this book for anyone just getting started with MySQL, but it as you get more proficient, you might want to pass it on to another MySQL newbie, as it may just gather dust on your bookshelf.



2. This book is part of a series of Visual Blueprint (tm) books. the subtitle reads Your visual blueprint to oepn source database mangement. There are others in this series on PHP, XML, and Javascript that I know of.
   
   The format is clear and obvious. Of course with the blue ink and the graphical layout, it is designed to resemble building plans or blueprints. The format is such that each ajoining pages tackle one command or subject. The subject is narrow in focus allowing you to concentrate on that one topic. Examples include topics such as Delete a Column, Understanding Date and Time Functions, View and manage running processes.
   
   On each two-page topic they have included four screen views that are annotated with helpful hints as to what has happened on the screen. Also there is a text portion that analyzes the specific command. On the right page is a text box titled "Extra" that goes into more depth.
   
   This rigid format makes the book easy to read and reference, but it also forces that authors to make a point in no more than several paragraphs sometimes limiting the topics effectivness.
   
   So I liked this book in the way its consistant design and format makes it very easy to read and learn the topics one step at a time. Looking forward to reading the other books in the series.

3 comments about Web Application Design and Implementation: Apache 2, PHP5, MySQL, JavaScript, and Linux/UNIX (Quantitative Software Engineering Series).

1. This is the book I wish I had had when I was starting to set up my Books-On-Line web site. Here in one simple step is just about half of what you need to know to set up a fairly complex database driven web site. I say about half of what you need to know because he spends no time at all on appearance, type fonts, color, illustrations, all that stuff. As he says in the introduction, he's not good at that (neither am I), and for those subjects you need another book.
   
   But for a functioning web site he recommends what is sometimes called LAMP - for Linux, Apache, MySql and PHP. To summarize why:
   
   The software is FREE, a very good price.
   It doesn't crash as often
   It runs faster so you can use a slower computer.
   
   By the time you finish, you'll probably want at least one book on each of these software packages, but here is an excellent place to start. It gives you enough to get started and you only need to go deeper into each of these packages when you start getting fancier. The nice thing about this book is that it gives you everything you need to get started in a well written, easy to understand way.
   
   Mr. Gabarro, there are two things I would suggest for your next edition: One, include a cd of a working collection of the four packages rather than saying go get any distribution, and two, talk a little about past and emerging technologies such as Cold Fusion for the past, and Ruby on Rails for the future. I'd be interested in your opinions.



2. Have read 40% of the book so far. There are many places where visual aspects are discussed, and there are no visual illustrations!!. The book is clearly aimed at people whose knowledge is elementary in the areas being discussed, and yet there is no attempt to make it easy for the reader to learn. Also, the examples are unimaginative.
   
   On the bright side, I like the casual conversational style.



3. Hi guys, first of all, thanks for actually considering buying this book. I do appreciate all reviews, whether they are good or bad, as this is the very first book I wrote. I do have to say in response to T.Arora that I did spend a lot of time writing this book (took me over a year), and the reason I did not include more images was a contractual restrictions. I was told to write a book of about 300 pages, and adding images would have made me go way over board. I felt it was more important to concentrate on explanations and the actual code. After that, you could always write the code and see what it looks like.
   
   I do hope you read it till the end. I've heard good things about the last chapter, when everything gets together. Hopefully you will like my examples a little better. :)
   
   For those thinking on whether or not to buy the book, realize that this book is about learning how to make database-driven websites, not how to make pretty pages. If you want to learn tricks and dangers of Web programming, the book can definitely help you. If you just want to learn Web design and how to choose colors, get a different book.
   
   Thanks to all of you that have purchased it so far! :)

5 comments about MySQL Bible with CDROM.

1. Very good book. I'll recomend it to anyone learning MySQL.

   Some examples did not work in my server but after contacting the author we/he resolved the problem. Problem was related to new release of PHP. The CD-ROM does not include the examples so be ready to do some typing.

   The pictures in the book are hard to see.

   Book content *****
   Book layout ***
   CD-ROM **
   Author's support *****




2. I purchased this book with great anticipation of expanding my knowledge of mySQL and making great us of the section on perl. Overall, I'm very dissapointed. The book itself goes into great detail about certain things that need not such a vast description, yet only privide single examples for some important things.
   The CD-ROM is useless. I was expacting it to have code from the book, whereas it's a collection of mySQL apps and programs that you can get free elswhere.
   Having explored the perl chapter of the book in greatest detail, it provides inadequite examples with a lot of inneficient coding.
   I give the book credit, however, for covering as much ground as it does, mySQL with perl, PHP and ODBC. Overall, however, not worth the money.



3. Don't waste your money on this. The book and reviews claim to include binaries and source of MySQL database but the CD-ROM contains neither. Bogus.



4. I have to disagree with many of the reviews of this book.
   
   The MySQL Bible would benefit from more than a simple layout change. Since the advent of the win installer for ver. 4.1.6 gamma of MySQL, the first 5 chapters of this book become useless. There are few explicit example of code (especially regarding how to interact with mysqladmin) extracted from the impossible "dark grey on black" screen captures that are used.
   
   As for the comment that some reviewers have made, that some of the codes provided (when they can be read) are inaccurate or ineffective, I would add only that I have yet to find a snippet of code in the book that actually works.
   
   Maybe there is something usefull in this book, but I haven't found it yet... I only hope that this book has a major revision for 5.0, and that someone in the editorial dept. at Wiley actually looks at pages before they are published.



5. Unfortunately, time and development have passed this book by. It is for MySQL 4.0, which has been FAR surpassed by the newer 5.0 version.
   
   As mentioned by some other reviewers, one of the main problems with the book is the illustrations. They are so dark as to be illegible. Not sure what the people that got the press proofs were thinking when they let that out the door.
   
   The author does a reasonable job on certain areas (hey, can't be all bad if he has a dedication to Eddie Van Halen).
   
   Might want to try the third edition of MySQL by Paul DuBois as a good reference book that is much more up-to-date.

5 comments about How to Do Everything with PHP and MySQL (How to Do Everything).

1. The good :
   ----------
   - Well structured content
   - The SQL part is not bad
   
   The Bad :
   ---------
   - hardly any explanation on why to use this or that function
   - very bad programming style (= spaggetti code)
   - gives you the example then you'll have to figure out how it works in a lot of cases
   
   Conclusion :
   ------------
   Not very enthousiast about this book, the SQL primer is nicely written (but a little limited), the php part is D-grade level..
   If looking for a good book about php and mySql turn to the book edited by Worx (see my other review)



2. If you want to work directly with HTML, PHP, and SQL without extra tools like PEAR, Smarty, Dreamweaver, etc., you may like this book. For small projects that do not need to be pretty and especially for learning how the code all works together, I like the approach of having the SQL, HTML, and PHP all on one page for a change. I am using the examples to convert an old ASP/Access project to PHP/MySQL and find the examples helpful.



3. I skimmed through this book once, and I read the reviews here. I thought this book could not have been that bad. It is a well structured book (from reading the Titles and SubTitles). Then I started reading it in details - lucky I borrowed this book from the library.
   
   This book started off so well. It promises "best practices", yet delivers very bad coding habits and taking shortcuts. The book outlines and titles were well designed, but the details were nothing more than, "Hay, here is the syntax, this is the usage plus some simple examples..., and you can use this to design database." Nothing that I couldn't find from the online PHP manual, and probably with better examples. Functions and keywords used were never explained properly. Its like, "Kid, now that I taught you addition, multiplication, subtraction and division.... You should be able to go out and solve the 2nd law of Thermodynamics because all mathematics built upon plus and minus."
   
   Not only that you can't do "Everything" reading this book, having read it I think I know less PHP.
   
   This book reflect badly on the publisher as well, I'd think twice buying similar book from them.



4. In the Introduction, the author claims that this book "is targeted at novice web developers". And true enough, the first two chapters guide the novice how to install and configure MySQL, PHP and Apache. Obviously these chapters have been written or thoroughly edited by an English speaking person. Then, from third chapter, the geek takes over ! He writes assuming that the reader has prior knowledge of PHP and MySQL, using terminology that he does not explain. In almost all chapters, instead of elaborating the subject under discussion, he suggests that the reader should look up the recommended website.
   
   I thoroughly recommend any book on PHP/MySQL written by any author other than Vikram Vaswani. I did not learn anything new from this book, which is "the worst" computer book I have ever read. How can any reputable House publish a book that consistently urges the reader to seek knowledge from elsewhere ?



5. Material is poorly presented. Author assumes programming knowledge on your part. You are often left floundering, wondering what the author meant. Found a much better book at my local library but it was, as you can imagine, seriously out of date. I have made it 1/3 of the way through this book and am considering tossing it in the trash.

5 comments about Upgrading to PHP 5.

1. This is a fantastic book. I frequently find that when an existing developer buys a book, he/she has to sort through all the garbage review in the beginning. This book assumes you are a competent PHP4 programmer. Then it takes you step by step through new PHP5 syntax and features that are unique to PHP5. It reviews and explains Object Oriented Programming (OOP), then discusses a variety of PHP5-only concepts, like SimpleXML and SQLite.
   
   I recently installed a PHP5 server and this book has been by my side since. All PHP4 developers who expect to use PHP5 within the next year or so should really have a copy of this book handy.



2. Being fairly proficient on PHP 4 but looking for more info on version 5, the idea of getting books on PHP 5 that, once again, starts from scratch wasn't exciting at all. This book instead was exactly what I needed, it assume you know PHP 4 and covers only the new features with a good amount of details and a bunch of useful suggestions for code migration. The only reason I don't give it 5 stars is that in the chapters covering OOP and DOM the author try to explain the new functionalities but also attempt to throw in the mix more generic info on this two topics. The end results are somewhat mixed, the coverage of PHP 5 is, in my opinion, very good, but the material about OOP and DOM instead aren't up to the rest and does more harm than good.



3. A very good choice. PHP5 is a new wave in dynamic web development. It dramaticly improved the handeling of classes and objects. This little book is your quick and easy to use refference of objects, methods, variables, scopes, functions. At Procreative Designs (procreative.ca), the company I work for this one was distributed all over our web development department at the beginning of last month. I personally find this book really handy and useful. Previously I owned PHP4 Refference and it always served me well. Overall its a great choice for quick refference.



4. The author does a great job summarizing common PHP characteristics and elaborating on PHP 5 improvements, with plenty of well-chosen code examples. Well suited for the established PHP programmer making the transition to PHP 5. For those starting out, use "Learning PHP 5" instead.



5. I own a sizable collection of O'Reilly books and have found them to in general be very well written and useful. "Upgrading to PHP 5" continues this tradition superbly.
   
   This book is _not_ for new PHP coders; the vast majority of the text assumes good familiarity with PHP 4.x. If you have this familiarity then you will find this book to be a thorough and well-organized primer on the many new features in the new PHP.
   
   The first chapter merely lists the major areas that have changed in the latest PHP, each of which roughly corresponds to a chapter in the book.
   
   Major enhancement to the OOP facilities of PHP are appropriately discussed in the next chapter. Unfortunately, this is probably the most clumsily written chapter due a strange desire to educate the reader in OOP basics (about the only place in the book where this mistake is committed). The result is a schism that imposes redundancy in the material while simultaneously making it unduly hard to locate specific topics.
   
   Thankfully the subsequent two chapters (on the new MySQL interface and the SQLite database) are uniformly well-written. Especially useful is a (perhaps oddly-situated) section on migration strategies from a PHP 4/MySQL 4.0 platform to a PHP 5/MySQL 4.1 platform.
   
   A chapter on XML follows, but I did not read it in great detail since my applications tend to not require it, so other reviewers are likely to provide greater insights here.
   
   Iterators, yet another feature completely new to PHP 5, are covered next. Unlike much of the conventional PHP fare (even OOP) this topic really does require understanding of rather abstract concepts (especially when debugging the RecusrsiveIterator interface). For this reason, while clearly written it may take hobbiests some time to take this material to heart.
   
   The new error-handling functions are introduced next. I think that the chapter could have benefited from a little more discussion; Trachtenberg seems to think providing code samples is almost self-explanatory. At the end of the day, though, the chapter does its job.
   
   The chapter on streams and filters is another one that I barely perused, so I defer to other reviewers on this topic.
   
   The penultimate chapter provides a very cursory evaluation of a handful of extensions to PHP. While certainly useful to the practicing PHP programmer they are covered in so brief a manner that you will need a separate text to implement them meaningfully. But this chapter does give enough information to at least evaluate the extensions' potential usefulness in an application.
   
   Trachtenberg concludes with an example PHP application. I do not like such examples in books - between space limitations and the complexity of real life this and other examples feel too... contrived... to be worthwhile. But I understand that it is included practically as canon, and do not fault the author for its inclusion.
   
   So, all things considered, this text covers the changes in PHP 5 in detail in a surprisingly brief 300 pages (and small page footprint). A worthy addition to a book collection, provided you already have general PHP reference available.

5 comments about MySQL/PHP Database Applications, 2nd Edition.

1. I loved this book. 2 years after reading it, I'm now programming php and mysql database applications professionally. This book is a great way to get started using php and mysql.



2. This is a great book, two years ago. I have spent more time and energy than I wish over the last two months trying to get the syntax differences down, and hunt down bugs in the code I'm writing. A new edition is out expected out in August, in which PHP 4.2 and MySQL 4.1 are to be covered. While no published book will keep up with the advancing of technologies that are standards today, this new edition will be much much closer to what is in use right now.

   Wait if you can, otherwise, you're in for a headache.




3. Unfortunately for me I spent the $40 for this book. What a mistake!
   
   When I first opened it up I was exited by the project management example in chapter 17. I told my wife I must have it! After I got home and started reading through it I decided to load the sample data into the my htdocs directory in my local Apache install. The nightmare never ended in getting the code to work. And this wasn't because I didn't set up the user accounts in MySQL! After messing around with it all weekend I decided to pay my fried a visit who is an expert web developer (builds web-enabled databases for California lobyists with millions of records). He looked at the code and found constructs that are specific to PHP5. The readme didn't say that I must install PHP5 for the examples to work. Anyway, after changing the code to conform to PHP4 syntax the examples still didn't work.
   
   I'm totally disappointed that I spent my hard earned dollars on this book. If the authors would be kind enough to post some code that works and is easy to follow, that would be a good step at repentance. Oh, one last thing, the authors make use of PEAR; that was a pain to install too. However, I got that working (with no instructions in the book) and the code still fails to work.
   
   Two thumbs down for this book.



4. I'm puzzled by the negative reviews. I'm a 30 year vet in computing, recently retired, and doing web/tech computing part time. I've needed to grasp parts of computing that I haven't been involved with, and boy did these guys get it right!
   
   I loved the comment about "The bulk of this chapter is for those of you who have made it to the early 21st century without working with relational databases!" That's me! And the writing was just right in terms of code hints and kinks along with clear explainations of database concepts.
   
   I'm reading the first edition, saw the second edition was out, and ordered it.
   
   I will agree, however, that there are *many* editing mistakes where they mistake terms or have errors in their tables/code. Hopefully the 2nd edition solves this.



5. When most individuals cover a topic in a non-fiction book they start generally then begin honing in on their topic. This book never seems to get to the specifics. They spend so much time introducing individuals to the topic of PHP and MySQL that they hardly ever get to specifics. When they do get to specifics they do a good job of covering what needs to be covered.
   This may be a result of the fact that the book was written by a number of authors. Overall it is a nice reference book to have and good if you are just beginning but not extremely valuable for experienced programmers.

5 comments about Ajax for Web Application Developers (Developer's Library).

1. First, let me agree with the previous reviewer who noted that this isn't an AJAX book for beginners. It isn't. I don't think anyone claimed that it was. It's a book for web application developers seeking to incorporate AJAX technology into web applications. I wouldn't expect a book with that kind of scope to be appropriate for beginners. This one certainly isn't, and I'm glad, having read enough beginner AJAX books that go over what an XmlHttpRequest is and explain some of the commonly used "stupid JavaScript tricks", dropping the names of popular frameworks and toolkits along the way without really supplying much information about them.
   
   Having said that: I've been seeking a book with the scope of this book for quite a while now. Not since Nicholas Zakas' book "Professional JavaScript for Web Developers" (which I still highly recommend) has this kind of in-depth coverage of the inner workings of AJAX been offered up. Zakas' book (only two years old) went into great detail about using Javascript to do all the cool things we now know as "AJAX"... without once using the word. (Two years ago the word "AJAX" hadn't reached its present buzzword saturation level, if it had been used much at all.)
   
   Hadlock revisits the technology now that AJAX and the various toolkits and frameworks supporting it (Dojo, script.aculo.us, Google Web Toolkit, etc.) have become commonplace. He doesn't provide a tutorial on how to use a particular toolkit or framework; instead, he explains how you can write an "engine" of your own. He starts with a good intro to AJAX, including explanations of how to use both XML and JSON in the response, moves on to the basic principles of object-oriented JavaScript, and then provides examples of reusable JavaScript components to include in your own JavaScript/AJAX engine. Whether you're seeking to reinvent the wheel and write such an engine yourself, or just have a hankering to understand how a toolkit like Dojo or script.aculo.us is constructed, this is great information. Where Zakas' book was an all-encompassing head first dive into deep JavaScript, this book is a briefer but still quite thorough tutorial that gets to the critical information quickly.
   
   The book also includes useful chapters on security and best practices.
   
   Where the book is lacking is in its coverage of server-side interaction. While it concentrates on PHP, it provides some examples of connecting to ASP.NET and ColdFusion, but... there's no mention whatsoever about Java/J2EE. (Ryan Asleson's "Pro Ajax and Java Frameworks" does provide that very sort of information, covering Struts, Spring, and JSF.) Still, where this book shines is in its in-depth explanation of how JavaScript/AJAX toolkits work and how you build your own or extend existing ones. This is still the only book I've seen that even attempts to do that.



2. Bought the book, liked the author's intent but I ran into one big problem. No source code for the book. I emailed the publisher last week and heard zero back from them.
   
   Note to publishers: Take care of your readers.
   
   I'm afraid customer service is dead. Maybe it has been outsourced.



3. I have attended Kris Hadlock's presentation in AJAXWORLD Conference & EXPO last week. I am glad I did because I really wanted to learn how to write reusable JavaScript libraries in my projects. His book is all about AJAX but engineering side of it. Why? because I found not many books out there show you how to capture server errors and record them for debugging and improvement in your project. Not many books show you how to implement the back-end for your frond-end applications. Not many books give you real-world examples. "
   Ajax for Web Application Developers" does all for you. It's very simple to understand Kris' codings and explanations because his book is neatly coded and implemented the coding standards.
   
   SOURCE CODES: Demonstrated examples in the book can be downloaded from the publisher. All you need to do is to create an account.
   
   I personally have many AJAX books in my library but specifically liked "Ajax for Web Application Developers".
   
   I strongly recommend it to those who are willing to learn in an easy way to create reusable JavaScript object-oriented libraries and understand the AJAX object methodology.
   
   Good luck



4. Kris did a really good job to be developer friendly. Even thought there are some "TODO" list in the sample code, the coding style is very clean, dood inbtro to Ajax MVC implementation. It could be better if Kris can go little deep, for example, Javascript OO, mini-MVC inside view object, feel the "display" will be too heavy if object has lots of events attached. Overall, it's a fine reading.



5. I am web designer and i have a multimedia and web developer company. I buy this book because i think that AJAX is the next generation of code for web API. This book is very good, it talk in developer language and you can learn about AJAX with single excercise.