mysqli_query为最后一行和最后一列发送null

$query = "SELECT * FROM table_name";
$result = mysqli_query($connection, $query);

$num_rows = mysqli_num_rows($result);
$num_cols = mysqli_num_fields($result);

// 移动结果集的指针到最后一行
mysqli_data_seek($result, $num_rows - 1);

// 遍历结果集的每一列，并将其值设置为null
for ($i = 0; $i < $num_cols; $i++) {
    // 移动结果集的指针到当前列
    mysqli_field_seek($result, $i);
    
    // 获取当前列的字段信息
    $field_info = mysqli_fetch_field($result);
    
    // 获取当前列的字段名
    $field_name = $field_info->name;
    
    // 更新最后一行当前列的值为null
    $query = "UPDATE table_name SET $field_name = NULL WHERE id = (SELECT MAX(id) FROM table_name)";
    mysqli_query($connection, $query);
}