In order to get the number of days in between 2 given dates using the getdaysbetween() when one of the inputs is in decimal form, I would use the following query in order to get the required output:
> select getdaysbetween(to_localdate('yyyy-MM-dd','2022-02-23'),to_localdate('yyyyMMddHHmmssSSS',(cast('text', <decimal date>))))
The to_localdate function converts a text value containing a datetime in specific format to a value of type localdate.
Since the to_date function is deprecated and may be removed in next major versions of Denodo Platform I would use the to_localdate function instead.
For more information, you could refer to the [Datetime Functions](https://community.denodo.com/docs/html/browse/8.0/en/vdp/vql/functions/datetime_functions/datetime_functions) section of the Virtual DataPort VQL Guide.
Hope this helps!