This is the command-line database client provided by oracle, and wow it's nasty. (Amazing concepts such as retrievable command history seem to have passed oracle by).
Once inside sqlplus here's a few helpful tips:
http://websvcs.itcs.umich.edu/how-to/sql.html - Has some helpful notes (and comparisons with mysql)
- If you can't see the contents of requests you're probably trying to view data which is longer than the default maximum length, so try something like:
set long 5000 set pages 5000