SQL Help!

[tregob42]

Calculate the average commission (name it as AverageCommission) earned by "Jeremy Tylor" between August 15, 2012 and August 31, 2012.

How do I get it to retrieve only one (Jeremy Tylor's) earnings?

[gandolf989]

This sounds a lot like homework to me. But here is some help anyway.
You are asking about an aggregate query, which implies that you should
use the group by clause, or only specify the aggregate function and where
clause that you need. you really want to learn this stuff, unless you are
just trying to pass a class.

http://docs.oracle.com/cd/B28359_01/server.111/b28313/aggreg.htm

I already gave you enough help to completely solve this, good luck.