Difference among "connect reset", "disconnect",

There are quite a lot of subtly differences:

CONNECT RESET and DISCONNECT are SQL statements, TERMINATE is a DB2 command.

From the manuals:

CONNECT RESET:
==============
On type 1 connections, it disconnects and runs a COMMIT before.
http://publib.boulder.ibm.com/infoc...in/r0000906.htm

On type 2 connections, it connects to the default database. But there are a
few more options to control what happens.
http://publib.boulder.ibm.com/infoc...in/r0000908.htm

DISCONNECT:
===========
Can only be used from an application and not interactively. Also, there
must not be an UOW running at the time of DISCONNECT.
http://publib.boulder.ibm.com/infoc...in/r0000943.htm

TERMINATE:
==========
Explicitly terminates the command line processor's back-end process.
http://publib.boulder.ibm.com/infoc...re/r0001973.htm
Through that, it also disconnects from the DB2 server.