The second MySQL library function called in showgifts( ) returns the number of rows that have been output by the query:

// Did we get back any rows?
if (@ mysql_num_rows($result) != 0) 
{

The function takes one parameter, the result set handle returned from mysql_query( ).

The last MySQL function called in showgifts( ) fetches the data:

// Fetch each database table row of the results
while($row = @ mysql_fetch_array($result))
{

This function retrieves row data, taking only the result set handle returned from mysql_query( ) as a parameter. Each call to mysql_fetch_array( ) fetches the next row of results and returns an array. In this example, the attributes are stored in the array $row. The function returns false when there are no more rows to fetch.

The attribute data stored in the array $row can be accessed associatively, that is, the attribute name can be used as a key to retrieve its value. For example, the following code prints the values of each presents table attribute as an HTML table row:

// Display the gift data as a table row
echo "
<tr>" .
     "
	<td>{$row["quantity"]}</td>" .
     "
	<td>{$row["present"]}</td>" .
     "
	<td>{$row["colour"]}</td>" .
     "
	<td>{$row["shop"]}</td>" .
     "
	<td>{$row["price"]}</td>";

The name of the attribute from the presents table—for example, quantity—is used as an index in the statement {$row["quantity"]}. The braces are a new feature in PHP that allow all variables to be included directly into strings that are delimited by double quotation marks; if a variable can be unambiguously parsed from within a double-quoted string, the braces can be omitted.

Here’s an example of the output of the above code fragment:

<tr>
  <td>1</td>
  <td>Baileys Comet 6 Ladder</td>
  <td>Silver</td>
  <td>Bunnings</td>
  <td>97.50</td>

The code in showgifts( ) also uses associative array access to produce embedded links for each gift, such as:

<td><a href="action.php?action=insert&amp;present_id=10">Add to Shopping List</a>

In this example, when the user clicks the link, the script action.php is requested, and two parameters are passed: action=insert and present_id=10. In response to these parameters, the script action.php inserts the gift with the present_id of 10 into the shopping list of the guest who’s logged in. The script is discussed later in Section 11.6.

There are three tricks to accessing data returned from mysql_fetch_array( ) :

Other MySQL library functions can be used to process result sets differently. These are discussed in Chapter 18. However, all of the basic techniques needed to develop a simple application are shown by the functions in this chapter.