>

>SELECT * FROM 
>   (SELECT TOP 10 * FROM A ORDER BY MyField
>   UNION ALL
>   SELECT TOP 10 * FROM B ORDER BY AnotherField) as x
>ORDER BY CommonField
>

This does not work. Putting TOP 10 in both selects causes the problem. As this is the most recent top 10 of everything, it has to be put outside of the derived table.