Many of my tables have fields with the values should not be changed.
These tables has on update triggers that update others tables.

For integrity of the data (in case of the value is changed), I have to
check if old.field <> new.field and raise exception or maintain
complicated triggers with update the others tables depending on the old
value too.

This syntax will be very helpful:

create table t
(
f integer not updatable
);

I think the flag can be stored in rdb$relation_fields.rdb$update_flag.
Check should be done at execution time because flag can be changed with
"alter table ... type ...".


Adriano