AS400 : Update and Join Sql commands

I searched for a while and I found Nothing. It looks like it is mandatory to use sentences like
UPDATE PROJECT

SET DEPTNO =
       (SELECT WORKDEPT FROM EMPLOYEE
        WHERE PROJECT.RESPEMP = EMPLOYEE.EMPNO)
WHERE RESPEMP='000030'

instead of using sentences with Join command :(

Note: If you find another way to do this, please let me know :) 

References: 

http://www2.systeminetwork.com/resources/clubtech/TNT400/bo400ng/sqlupdatejoin.htm
http://publib.boulder.ibm.com/cgi-bin/bookmgr/BOOKS/QB3AQ802/5.2 

http://www.experts-exchange.com/Database/DB2/Q_22535124.html