Re: Dumping/Restoring with constraints?

Is there a mechanism to check exactly which row may have characters
that are not UTF8? I am trying with this kind of a command:

select id from employee
where modify_date between '2008-03-01' and '2008-07-01'
and joint_field_of_name_etc <> convert(joint_field_of_name_etc, 'UTF8')

This is of course not the best way of doing so. Is there a better
system-provided way of checking for rows that may not be UTF8?  Or to
even have a constraint to this effect, to disallow any non-UTF8 data
from getting in there?

Thanks