<p>Can databases (MySQL in particular, any SQL--MS, Oracle, Postgres--in general) do mass updates, and figure out on their own what the new value should be? Say for example I've got a database with information about a bunch of computers, and all of these computers have drives of various sizes--anywhere from 20 to 250 GB. Then one day we upgrade every single computer by adding a 120 GB hard drive. Is there a way to say something like</p>

<pre><code>update computers set total_disk_space = (whatever that row's current total_disk_space is plus 120)
</code></pre>

Yeah:
```
```
update computers set total_disk_space = total_disk_space + 120;
```
```