text: --Q4.1
  set schema 'ssb';
  select 
      d_year, c_nation,
      sum(lo_revenue - lo_supplycost) as profit
  from 
      dates, customer, supplier, part, lineorder
  where 
      lo_custkey = c_custkey
      and lo_suppkey = s_suppkey
      and lo_partkey = p_partkey
      and lo_orderdate = d_datekey
      and c_region = 'AMERICA'
      and s_region = 'AMERICA'
      and (p_mfgr = 'MFGR#1' or p_mfgr = 'MFGR#2')
  group by 
      d_year, c_nation
  order by 
      d_year, c_nation;
  