insert into table1
select some_cols
from (merge into table1 using(full join) .... out some_cols)

merge into table1 a
using
(
    select coalesce(t2.id , t1.id) id,
           t2.code,
           t2.name,
           case when c.lvl = 2 then 'upd'
                               when t2.rowid is null then 'del'
                               when t2.checksum = t1.checksum then 'dummy'
                               else 'ins'
           end flag,
           t2.checksum
    from table2 t2
  full join
    (select id, checksum  from table1 where is_active = 1) t1  
  on t2.id = t1.id
   join lateral(select level lvl 
               from dual 
               connect by level <= case when t2.checksum != t1.checksum
                                     then sign(t1.id) + sign(t2.id) end) c on 1=1
) b
on (a.id = b.id and b.flag in ('upd', 'del', 'dummy'))
when matched then
	update
  set date_end = sysdate,
      is_active = 0,
      is_deleted = case when b.flag = 'del' then 1 else 0 end
  where  a.is_active = 1
    and b.flag != 'dummy'
when not matched then
	insert (id, code, name, checksum, date_begin, date_end, is_active, is_deleted)
  values (b.id, b.code, b.name, b.checksum, sysdate, date '3000-12-31', 1, 0);