cfupdate action using query

You say cfupdate, so I'm assuming an existing row in the second datasource. Cfupdate needs the form scope, so you could do something like this:

<cfquery name="getRow" datasource="firstDsn">
select *
from tbl
where primaryKeyColName = {primary key value}
</cfquery>

<cfloop list="#getRow.columnlist#" index="colName">
<cfparam name="form[colName]" default="#getRow[colName][1]#">
</cfloop>
<!--- have assumed same table name --->
<cfupdate datasource="secondDsn" tablename="tbl">
update done

<!---
<cfinsert datasource="secondDsn" tablename="tbl">
--->

It might be possible. You'd be using cfinsert though, not cfupdate.