I have two field name `$date` and `$time`. 

```
     date  |  time
2011/01/09 | 08:22:25
2011/01/09 | 13:00:55
2011/01/09 | 17:45:18
2011/01/09 | 17:30:26
2011/01/08 | 18:22:00
2011/01/08 | 12:06:39

```

How to let the newest before the oldest. I want them to be: 

```
     date  |  time
2011/01/09 | 17:45:18
2011/01/09 | 17:30:26
2011/01/09 | 13:00:55
2011/01/09 | 08:22:25
2011/01/08 | 18:22:00
2011/01/08 | 12:06:39

```

How to write a `select * from article order by...desc...`? Thanks.