不过这样的话，就无法得到生成的SQL字符串了。。。

$address = "Delaware St";

$sql = "SELECT * FROM WiFiHotSpots WHERE ItemName = ? AND ItemID < 15 AND ItemAddress = ?";
$stmt = $dbh->prepare($sql);
$stmt->execute(array($name, $address));
$row = $stmt->fetch();
echo "(" . $row["ItemLatitude"] . ", " . $row["ItemLongitude"] . ")";

判断记录集是否为空：
if (!$stmt->rowCount()) {
  echo "记录集为空";
}

$stmt->rowCount()可以直接当布尔值用。

原始方法：
if (mysql_num_rows($rs) == 0) {
echo "记录集为空";
}

回复：33楼
http://php.net/manual/en/pdostatement.debugdumpparams.php
debugDumpParams可以用来输出SQL及其参数，但是无法产生目标SQL。

Error SQL query:

SELECT * FROM WiFiHotSpots WHERE ItemName = ? AND ItemID < 15 AND ItemAddress = ? LIMIT 0, 25
MySQL said:
#1064 - You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near '? AND ItemID < 15 AND ItemAddress = ?
LIMIT 0, 25' at line 1

bindColumn的用法：
<?php
include_once("conn.php");

$sql = "SELECT * FROM WiFiHotSpots";
$stmt = $dbh->prepare($sql);
$stmt->execute();

$stmt->bindColumn("ItemSuburb", $suburb);
foreach ($stmt as $row) {
    echo $suburb . "<br>";
    // $suburb is equivalent to $row["ItemSuburb"]
}
?>

bindColumn将一个字段绑定到一个php变量中，也就是每次循环自动执行：
$suburb = $row["ItemSuburb"]