使用更新联接：

UPDATE master_table AS m
SET zipcode = t.zipcode
FROM temp_table t
WHERE m._id = t._id

您可以使用WITH来获取只需要更新的数据。
此方法允许您开发和测试选择查询，并通过两个步骤将其转换为更新查询。

with t as (
  select m._id, t.zipcode as new_zipcode
  from master_table m
  inner join temp_table as t on t._id = m._id and t.zipcode <> m.zipcode
)
update master_table m
set zipcode = t.new_zipcode
from t
where m._id = t._id

Demo here
要更新多列，只需将它们添加到inner join中，当然还要将它们添加到SET子句中：

with t as (
  select m._id, t.zipcode, t.column2
  from master_table m
  inner join temp_table as t on t._id = m._id and ( t.zipcode <> m.zipcode or t.column2 <> m.column2)
)
update master_table m
set zipcode = t.zipcode, column2 = t.column2
from t
where m._id = t._id

Demo here