Coalesce in query with timeGroupAlias and timeFilter

I’m trying to query from a Postgres table and display resulting metrics in a Graph panel.

The Postgres table has log entries with two date columns per row: CreationDate and LastLogDate. CreationDate always has the first logged date, and LastLogDate has the date of the last occurrence of the same log type.

With the Grafana query builder, I get the following query:

SELECT
  $__timeGroupAlias("CreationDate",$__interval,NULL),
  "ApplicationName" AS metric,
  max("DuplicateCount")
FROM "Errors"
WHERE
  $__timeFilter("CreationDate")
GROUP BY 1,2
ORDER BY 1,2

It works fine, except that I want to group & filter by LastLogDate if it’s not null, instead of CreationDate, but I’m not sure how to specify a coalesce (take first non-null value) function along with $__timeGroupAlias and $__timeFilter functions. It this possible somehow?