Update with aggregate - sql

Question

I'm having trouble changing an update from Oracle to SQL Server
I have doubt in an update in SQL Server. In Oracle, I managed to do it, but in SQL Server, I'm not getting it.
Below are the two examples (Oracle worked, however SQL Server returns the error:
An aggregate may not appear in the list of sets of an UPDATE statement.
Oracle
UPDATE
tab1
SET
(t1.va, t1.vb) = (
SELECT
sum(
CASE
WHEN (t2.date2 - t2.date1) <= 30 THEN Coalesce((t2.x + t2.y), 0)
END
) * 100,
sum(
CASE
WHEN (t2.date2 - t2.date1) <= 60
AND (t2.date2 - t2.date1) > 30 THEN Coalesce((t2.y + t2.z), 0)
END
) * 100
FROM
tab2 t2
WHERE
t2.cd_xyz = tab1.cd_xyz
);
SQL Server
UPDATE
tab1 t1
SET
t1.va = sum(
CASE
WHEN (t2.date2 - t2.date1) <= 30 THEN COALESCE((t2.x + t2.y), 0)
END
) * 100,
t1.vb = sum(
CASE
WHEN (t2.date2 - t2.date1) <= 60
AND (t2.date2 - t2.date1) > 30 THEN COALESCE((t2.y + t2.z), 0)
END
) * 100
FROM
tab2 t2
INNER JOIN tab1 t1 ON t2.cd_xyz = t1.cd_xyz;

Answer 1

You need to calculate the values you want to use in a sub-query then join then onto the table you are updating using the UPDATE ... FROM syntax from the documentation.
I'm not totally sure I've expressed your logic correctly given you didn't have any grouping, but did have a sum, but it should be enough to get you started.
UPDATE tab1 SET
va = t2a.vaNew
, vb = t2a.vbNew
FROM tab1
INNER JOIN (
SELECT
cd_xyz
, SUM(
CASE
WHEN (t2.date2 - t2.date1) <= 30 THEN COALESCE((t2.x + t2.y), 0)
END
) * 100 as vaNew
, SUM(
CASE
WHEN (t2.date2 - t2.date1) <= 60
AND (t2.date2 - t2.date1) > 30 THEN COALESCE((t2.y + t2.z), 0)
END
) * 100 AS vbNew
FROM tab2 t2
GROUP BY cd_xyz
) AS t2a ON t2a.cd_xyz = t1.cd_xyz;