to update a table with values from another table

[lunas]

hi
i have to update a table based on a criteria with value selected from another table. i am writting a java progg for it . i just want to know can it be done with one statement.

my purpose is

result set rs =select (ID) from Tab1 where colmB is null

LOOP rs

select ID2 from tab2 where colC=ID

update tab3 set colD=ID2 where colC=ID and colD is null

end LOOP

hope i have explained my problem clearly...
can anyone please help me in this..

[debasisdas]

yes it can be easily done

can you please post structure of both the tables involved in the update statment.