Database query using Java

I was wondering if anybody out there has ever created a java service to query a remote database? I have a record structure as follows:

RL1
-T1
-T2
-T3
–RL2
—T1
—T2
—T3

RL=Record List
T=Text Field

Is it possible to perform the following all within a java service?

a) read in the entire record list
b) loop over record list one
c) loop over record list two
d) now run a query using the value in T2
e) the result if returned mapped back into T2