I have two tables with two similar fields point_value and id. I am trying to update table_tmp based on values from table_assn but keep getting error message ORA-01427: single-row subquery returns more than one row. I will appreciate any help on getting the update accomplished.

update table_tmp a
set a.point_value = (select b.point_value
from table_assn b,
where b.id = a.id
and b.point_value != a.point_value)