如何为每一行更新不同的值？

Question

我有一个predicted_data的postgres表：

 id | lat | lon | predicted
----+-----+-----+-----------
  1 |   1 |   1 |         10
  2 |   2 |   2 |         20
  3 |   3 |   3 |         30

我还有另一个observed_data表：

 id | lat | lon | observed | error
----+-----+-----+----------+-------
  1 |   1 |   1 |       11 |
  2 |   2 |   2 |       25 |
  3 |   3 |   3 |       32 |

我想填充error的{​​{1}}列。对于第一行，我会这样做：

observed_data

我是否可以通过某种方式编写此查询，以便同时对每一行进行查询？

我的最终结果应该是：

UPDATE observed_data 
SET error = 
((SELECT predicted FROM predicted_data WHERE lat = 1 AND lon = 1) - (SELECT observed FROM observed_data WHERE lat = 1 AND lon = 1)) 
WHERE lat = 1 AND lon = 1 AND id = 1;

Answer 1

您可以对联接使用UPDATE：

update observed_data as od
  set error = pd.predicted - od.observed
from predicted_data as pd 
where (pd.lat, pd.long) = (od.lat, od.long);