I recently found an interesting tool to play with databases, SQLFiddle
The tool is used to share some fragments of code, running on a live database, to allow users to not only see (read) the code, but also actually execute it, to play with the code.
See this link
for all the details.
The nice part is that MySQL 5.5 is part of the supported databases, try it here
It gets better: MySQL 5.6 is also there, so you get to try new 5.6 features
, or your favorite query, in a blink, without having to do an installation.
And icing on the 5.6 cake, the PERFORMANCE_SCHEMA is also enabled, with grants given to the user to query performance schema tables.