How to update and insert automatically

Question

Hi all,
I am having two tables, old and new (first column is PKey in two tables)
NEW
5     col2     col3     col4
6     col2     col3     col4
1     col2     col3     col44
2     col2     col3     col4
3     col2     col33     col4
4     col2     col3     col4
OLD
1     col2     col3     col4
2     col2     col3     col4
3     col2     col3     col4
4     col2     col3     col4
I want to update/insert in OLD table from the NEW tables values.
I think i will use MERGE statement, but sometimes, the column value will
change (PKey didnot change), so MERGE wont work here.
With MINUS statement, i will get the differences
select COL1, COL2, COL3, COL4
from NEW
minus
select COL1, COL2, COL3, COL4
from OLD;
1     col2     col3     col44
3     col2     col33     col4
5     col2     col3     col4
6     col2     col3     col4
I want to update/insert these values Remotely in OLD (OLD table actually in Remote). I cannot send all the data of NEW table to remote because the data is very large. So, i have to take the differences and i have to send those differences to Remote and i have to update/insert remotely.
Any help is appreciated.
Thanks in advance
Pal

Answer 1

try like this:
merge
into old t
      using (
              select COL1, COL2, COL3, COL4
                from NEW
              minus
              select COL1, COL2, COL3, COL4
                from OLD
            ) v
         on (v.col1 = t.col1)
when matched
   then update set t.col2 = v.col2, t.col3 = v.col3, t.col4 = v.col4
when not matched
   then insert(col1, col2, col3, col4) values(v.col1, v.col2, v.col3, v.col4)