Is SQL VALUES() possible in UPDATE?

Hi

I like using VALUES in SQL as a way to give a short name to an
expression or a substring, but I haven't yet tried to use it in an
update statement (where the data comes from within the record itself).
Is it possible?

Consider the following alteration to a flat file, which replaces the
text at pos. 57 for 30 characters, prepending PAYMORE to the string if
it doesn't already contain PAYMORE, and does contain 'Sales' or
'Branch' (or is 'NYC'), and the statement simultaneously removes
'Sales' and/or 'Branch':

update FLATFL
set FLDATA =
overlay(FLDATA placing
'PAYMORE ' || substr(replace(replace( substr(FLDATA,57,30) ,
'Branch',''),'Sales',''),1,22)
from 57 for 30)
where upper(substr(FLDATA,57,30)) not like '%PAYMORE%'
and ( regexp_like( substr(FLDATA,57,30) ,'(Sales|Branch)') OR
substr(FLDATA,57,30) = 'NYC')

So, for instance 'Baltimore Sales' would become 'PAYMORE Baltimore'
(has a nice ring to it), and 'NYC' would become 'PAYMORE NYC'.

This works, but as you can see, "substr(FLDATA,57,30)" is defined four
times, which is not very elegant. It would be nice to be able to
define it once and refer to it by name. But without a FROM or a WITH,
I can't figure out how to get a VALUES clause in there.

Thanks,

Arnie.