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Học php, mysql và javascript - p 28

Cách chính mà người sử dụng trang web tương tác với PHP và MySQL là thông qua việc sử dụng các hình thức HTML. Chúng được giới thiệu rất sớm trong sự phát triển của World Wide Web vào năm 1993-ngay cả trước khi sự ra đời của thương mại điện tử và có vẫn là một trụ cột kể từ đó, do sự đơn giản và dễ sử dụng. | CHAPTER 11 Form Handling The main way that website users interact with PHP and MySQL is through the use of HTML forms. These were introduced very early on in the development of the World Wide Web in 1993 even before the advent of e-commerce and have remained a mainstay ever since due to their simplicity and ease of use. Of course enhancements have been made over the years to add extra functionality to HTML form handling so this chapter will bring you up to speed on state-of-the-art form handling and show you the best ways to implement forms for good usability and security. Building Forms Handling forms is a multipart process. First a form is created into which a user can enter the required details. This data is then sent to the web server where it is interpreted often with some error checking. If the PHP code identifies one or more fields that require reentering the form may be redisplayed with an error message. When the code is satisfied with the accuracy of the input it takes some action that usually involves the database such as entering details about a purchase. To build a form you must have at least the following elements An opening form and closing form tag A submission type specifying either a get or post method One or more input fields The destination URL to which the form data is to be submitted Example 11-1 shows a very simple form created using PHP. Type it in and save it as formtest.php. 251 Example 11-1. formtest.php a simple PHP form handler php formtest.php echo _END html head title Form Test title head body form method post action formtest.php What is your name input type text name name input type submit form body html _END The first thing to notice about this example is that as you have already seen in this book rather than dropping in and out of PHP code the echo _END._END construct is used whenever multiline HTML must be output. Inside of this multiline output is some standard code for commencing an HTML document displaying its title and starting