> >>If you're only interested in an approximate count of records in one
> or more tables,
>
> How does one get an approximate count, you either count your records or
> you don't

You either count records (to get exact number),
or you count number of distinct entries in index (to get approximate count).

>
> How could one write the SQL -
>
> - Mr Query could you please go and "guess" how many records there are :-)

Did you read the link send by Set ?
http://groups.yahoo.com/group/firebird-support/message/61513

Ivan