根据MySQLi绑定结果确定双字段是否为空

$mysqli = new mysqli("localhost", "username", "password", "database");
if ($mysqli->connect_errno) {
    echo "Failed to connect to MySQL: " . $mysqli->connect_error;
    exit;
}

$query = "SELECT field1, field2 FROM table";
$stmt = $mysqli->prepare($query);
$stmt->execute();
$stmt->bind_result($result1, $result2);

while ($stmt->fetch()) {
    if ($result1 === null && $result2 === null) {
        echo "Both fields are empty";
    } elseif ($result1 === null) {
        echo "Field1 is empty";
    } elseif ($result2 === null) {
        echo "Field2 is empty";
    } else {
        echo "Both fields are not empty";
    }
}