PHP DOM XML输出:缺少数据集

Question

在MYSQL数据库上使用php查询，并使用DOM输出xml文件，一切都很正常，只是并不是所有的数据集都写入到xml文件中。例如，我可以给出预期结果的数量：

$num_results = mysql_num_rows($result);
echo $num_results;

其例如是20，但是在所保存的xml文件("auswertung.xml")中仅存在19个条目。每次都不会写入第一个数据集。会出什么问题呢？

下面是相关的代码片段：

// Start XML file, create parent node
$dom = new DOMDocument("1.0");
$node = $dom->createElement("markers");
$parnode = $dom->appendChild($node);

// Opens a connection to a mySQL server
$connection=mysql_connect ($dbhost, $username, $password);
if (!$connection) {
    die('Not connected : ' . mysql_error());
}

// Set the active mySQL database
$db_selected = mysql_select_db($database, $connection);
if (!$db_selected) {
    die ('Can\'t use db : ' . mysql_error());
}


$query = "SELECT * FROM Herpeto WHERE Art like '$Art' ORDER BY ID ASC";
$result = mysql_query($query) or die ("Error in query: $query " . mysql_error());
$row = mysql_fetch_array($result);
$num_results = mysql_num_rows($result);

// Iterate through the rows, adding XML nodes for each
echo $num_results;
while ($row = @mysql_fetch_assoc($result)){
// ADD TO XML DOCUMENT NODE
$node = $dom->createElement("marker");
$newnode = $parnode->appendChild($node);

$newnode->setAttribute("Art", $row['Art']);
$newnode->setAttribute("Anzahl", utf8_encode ($row['Anzahl']));
$newnode->setAttribute("Status", $row['Status']);
$newnode->setAttribute("Stadt", utf8_encode($row['Stadt']));
$newnode->setAttribute("Fundstelle", utf8_encode($row['Fundstelle']));
$newnode->setAttribute("Bemerkung", utf8_encode($row['Bemerkung']));
$newnode->setAttribute("Tag", utf8_encode ($row['Tag']));
$newnode->setAttribute("Monat", utf8_encode ($row['Monat']));
$newnode->setAttribute("Jahr", utf8_encode ($row['Jahr']));
$newnode->setAttribute("Beobachter", utf8_encode($row['Beobachter']));
$newnode->setAttribute("lat", $row['lat']);
$newnode->setAttribute("lng", $row['lng']);
}

$dom->save('auswertung.xml');

Answer 1

输出中的20行中有19行，因为您在将结果传递给while循环之前调用了mysql_fetch_array()，在while循环中实际进行了xml输出：

$row = mysql_fetch_array($result); // <-- here you get the first row
//...
while ($row = @mysql_fetch_assoc($result)){ // <-- now while loop starts from 2nd row