Wijzigingen berekenen in Oracle sql

Probeer dit:

select t.* 
, case when attr1 != LAG(attr1, 1, attr1) OVER (PARTITION BY hid_1, hid_2 ORDER BY attr5) then 1 else 0 end +
  case when attr2 != LAG(attr2, 1, attr2) OVER (PARTITION BY hid_1, hid_2 ORDER BY attr5) then 1 else 0 end +
  case when attr3 != LAG(attr3, 1, attr3) OVER (PARTITION BY hid_1, hid_2 ORDER BY attr5) then 1 else 0 end +
  case when attr4 != LAG(attr4, 1, attr4) OVER (PARTITION BY hid_1, hid_2 ORDER BY attr5) then 1 else 0 end as attr6
from t