"xtron" <xtronz(at)yandex(dot)ru> writes:
> this is NOT work:
> update a1 set a1.value = a2.value from a2 where a1.id = a2.id;
This syntax is disallowed by the SQL standard: a SET target is just the
name of the column. If we tried to interpret it as you suggest then
we'd be incompatible for composite-type columns.
regards, tom lane