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This chapter is from the book

Creating a Sample Application: Bob’s Auto Parts

One of the most common applications of any server-side scripting language is processing HTML forms. You’ll start learning PHP by implementing an order form for Bob’s Auto Parts, a fictional spare parts company. You can find all the code for the examples used in this chapter in the directory called chapter01 on the CD-ROM.

Creating the Order Form

Bob’s HTML programmer has set up an order form for the parts that Bob sells. This relatively simple order form, shown in Figure 1.1, is similar to many you have probably seen while surfing. Bob would like to be able to know what his customers ordered, work out the total prices of their orders, and determine how much sales tax is payable on the orders.

Figure 1.1

Figure 1.1 Bob’s initial order form records only products and quantities

Part of the HTML for this form is shown in Listing 1.1.

Listing 1.1 orderform.html—HTML for Bob’s Basic Order Form

    <form action="processorder.php" method="post">
    <table style="border: 0px;">
    <tr style="background: #cccccc;">
      <td style="width: 150px; text-align: center;">Item</td>
      <td style="width: 15px; text-align: center;">Quantity</td>
    </tr>
    <tr>
      <td>Tires</td>
      <td><input type="text" name="tireqty" size="3"
     maxlength="3" /></td>
    </tr>
    <tr>
     <td>Oil</td>
     <td><input type="text" name="oilqty" size="3"
      maxlength="3" /></td>
    </tr>
    <tr>
     <td>Spark Plugs</td>
     <td><input type="text" name="sparkqty" size="3"
        maxlength="3" /></td>
    </tr>
    <tr>
     <td colspan="2" style="text-align: center;"><input type="submit" value="Submit
Order" /></td>
    </tr>
    </table>
    </form>

Notice that the form’s action is set to the name of the PHP script that will process the customer’s order. (You’ll write this script next.) In general, the value of the action attribute is the URL that will be loaded when the user clicks the Submit button. The data the user has typed in the form will be sent to this URL via the HTTP method specified in the method attribute, either get (appended to the end of the URL) or post (sent as a separate message).

Also note the names of the form fields: tireqty, oilqty, and sparkqty. You’ll use these names again in the PHP script. Because the names will be reused, it’s important to give your form fields meaningful names that you can easily remember when you begin writing the PHP script. Some HTML editors generate field names like field23 by default. They are difficult to remember. Your life as a PHP programmer will be easier if the names you use reflect the data typed into the field.

You should consider adopting a coding standard for field names so that all field names throughout your site use the same format. This way, you can more easily remember whether, for example, you abbreviated a word in a field name or put in underscores as spaces.

Processing the Form

To process the form, you need to create the script mentioned in the action attribute of the form tag called processorder.php. Open your text editor and create this file. Then type in the following code:

<_pre><!DOCTYPE html>
<html>
  <head>
    <title>Bob's Auto Parts - Order Results</title>
  </head>
  <body>
    <h1>Bob's Auto Parts</h1>
    <h2>Order Results</h2>
  </body>
</html>

Notice how everything you’ve typed so far is just plain HTML. It’s now time to add some simple PHP code to the script.

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