$sql = 'SELECT name, pwd
FROM person
where name="daxiong"';
$retval = mysqli_query( $conn, $sql );
if(! $retval )
{
die('无法读取数据: ' . mysqli_error($conn));
}else{
echo '读到数据';
$row = mysqli_fetch_array($retval, MYSQL_ASSOC);
$name .=$row['name'];
$pwd .=$row['pwd'];
}