>I checked version 9 and this update works
>
>update site set ss.siteCat = 1
>from site as ss join trans t
>on t.siteno = ss.siteno
>where ss.recno = 9000016

Ok, this syntax is a little bit different than in my example. In my example, the Update clause includes the alias and not the table name. Maybe we should had only to replace the Update clause with the table name instead of the alias.