Managing & Using MySQL, 2nd Edition

Handling Results

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 "\n<tr>" .
     "\n\t<td>{$row["quantity"]}</td>" .
     "\n\t<td>{$row["present"]}</td>" .
     "\n\t<td>{$row["colour"]}</td>" .
     "\n\t<td>{$row["shop"]}</td>" .
     "\n\t<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 ...