[Exim] alias per domain in mysql

Hi!

I wonder how to do an alias per-domain-lookup in mysql. of course not
completely... I want to "convert"

virtual:
  domains       = dbm;/etc/exim/domains-virtual.db
  driver        = aliasfile
  file          = /etc/exim/alias/$domain

to

alias_domain:
  domains = mysql;MYSQL_LOCALDOMAINS
  driver = aliasfile
  search_type = mysql
  query = "select zieladdresse from
  alias_${tr{${domain}}{-\.}{\_}} \
        where username='$local_part'"

which works fine, but this

virtual-banking:        luemmel@???
*:                      luemmel2@???

asterisk must be handled otherwise, but how?
now i have userid-address pairs in my table and an asterisk-address
pair, whi, of course, does not work ....

KONSTI