SQL 更新查询中的聚合函数?

问题描述：

我试图将一个表中的值设置为另一个表中值的总和.一些类似的东西:

I'm trying to set the value in one table to the sum of the values in another table. Something along these lines:

UPDATE table1
SET field1 = SUM(table2.field2)
FROM table1
INNER JOIN table2 ON table1.field3 = table2.field3
GROUP BY table1.field3

当然，就目前而言，它是行不通的 - SET 不支持 SUM 并且不支持 GROUP BY>.

Of course, as this stands, it won't work - SET doesn't support SUM and it doesn't support GROUP BY.

我应该知道这一点，但我的脑子里一片空白.我做错了什么?

I should know this, but my mind's drawing a blank. What am I doing wrong?

答

UPDATE t1
SET t1.field1 = t2.field2Sum
FROM table1 t1
INNER JOIN (select field3, sum(field2) as field2Sum
   from table2
  group by field3) as t2
on t2.field3 = t1.field3

SQL 更新查询中的聚合函数?

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