<t>You don't quite have SQL Server's proprietary UPDATE FROM syntax down. Also not sure why you needed to join on the CommonField and also filter on it afterward. Try this:<br/>
<br/>
UPDATE t1<br/>
SET t1.CalculatedColumn = t2.[Calculated Column]<br/>
FROM dbo.Table1 AS t1<br/>
INNER JOIN dbo.Table2 AS t2<br/>
ON t1.CommonField = t2.[Common Field]<br/>
WHERE t1.BatchNo = '110';<br/>
<br/>
```<br/>
<br/>
If you're doing something silly - like constantly trying to set the value of one column to the aggregate of another column (which violates the principle of avoiding storing redundant data), you can use a CTE (common table expression) - see [here](http://technet.microsoft.com/en-us/library/ms190766.aspx) and [here](https://sqlblog.org/2016/01/06/s1-backtobasics-ctes) for more details:<br/>
<br/>
```<br/>
;WITH t2 AS<br/>
(<br/>
SELECT [key], CalculatedColumn = SUM(some_column)<br/>
FROM dbo.table2<br/>
GROUP BY [key]<br/>
)<br/>
UPDATE t1<br/>
SET t1.CalculatedColumn = t2.CalculatedColumn<br/>
FROM dbo.table1 AS t1<br/>
INNER JOIN t2<br/>
ON t1.[key] = t2.[key];<br/>
<br/>
```<br/>
<br/>
The reason this is silly, is that you're going to have to re-run this entire update every single time any row in `table2` changes. A `SUM` is something you can always calculate at runtime and, in doing so, never have to worry that the result is stale.</t>
