Aggregate function in an SQL update query?

sql, sql-server, t-sql

Solution

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

Problem

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 ``` Of course, as this stands, it won't work - `SET` doesn't support `SUM` and it doesn't support `GROUP BY`. I should know this, but my mind's drawing a blank. What am I doing wrong?

Original source

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