Help needed in MERGE statement

Question

Hi,
I am new to PL/SQL, I want to update a table called "final_test" based on the below query result.
1. I want to check whether that particular record is present or not in my "final_test" table.
2. If its present in the "final_test" table and the process_status got changed then I want to update that alone in my "final_test" table.
3. If its not present then I want to insert that record into my "final_test" table.
Basically I am retrieving the report and its status for a particular date.
select
b.id,
a.name,
a.t_name,
c.process_status,
c.time_process
from rep_tab_map a, j_tab_map b, proc_status c
where a.t_name=b.t_name
and b.id=c.id (+)
and trunc(c.date_start)=trunc(sysdate -1)
group by a.name,b.id,c.process_status,c.time_process,a.t_name
order by 2
I thought of using Merge statement but i am not sure what i have to use in ":USING" and "ON" clause.
Please help me with MERGE or with someother way.
Thanks

Answer 1

Assuming final_test has same structure as select list in your query:
merge
  into final_test a
  using (
         select  b.id,
                 a.name,
                 a.t_name,
                 c.process_status,
                 c.time_process
           from  rep_tab_map a,
                 j_tab_map b,
                 proc_status c
           where a.t_name=b.t_name
             and b.id=c.id(+)
             and trunc(c.date_start)=trunc(sysdate -1)
           group by a.name,b.id,c.process_status,c.time_process,a.t_name
        ) b
  on (b.id = a.id)
  when matched then update set a.name = case a.process_status
                                          when b.process_status then a.name
                                          else b.name
                                        end,
                               a.t_name = case a.process_status
                                            when b.process_status then a.t_name
                                            else b.t_name
                                          end,
                               a.process_status = b.process_status,
                               a.time_process = case a.process_status
                                                  when b.process_status then a.time_process
                                                  else b.time_process
                                                end
  when not matched then insert(
                               a.id,
                               a.name,
                               a.t_name,
                               a.process_status,
                               a.time_process
                        values(
                               b.id,
                               b.name,
                               b.t_name,
                               b.process_status,
                               b.time_process
/SY.