Query MySQL Database On-The-Go
There are plenty of web based admin tools - PHPMyAdmin for MySQL (installed it once - seems OK and is widely used).

The MySQL Workbench tool is top-notch for administering MySQL - if you can telnet/ssh into your box, you can use it - I would recommend this approach as your starting point.

As a general tool, I also recommend SQuirreL SQL - a JDBC based tool - some shops can have strange requirements re. 3rd party tools and the like - worth looking at also!