count_distinct | An extension with alternative to COUNT

I have browsed the other answers relating to grouping aliased columns but I believe what I am attempting to do is very common and I am super confused as to why this would create such a complex query that would require a ton of subqueries or CTEs. My goal is to look at different columns that are currently in use and determine the percentage of null or distinct values in each column. To do this, I am simply trying to apply the same logic to all of the for multiple different fields (400) in a new column for each column/variable. I would like my result table to look like this:

Let's imagine that I have the following data on a QuestDB table:

We have a list of tasks on the website that all users need to perform before they are able to apply for a job. Tracked by Events

I'm able to create a table by userid that shows all the task that were completed by that user and then I'm able to create a table that shows distinct count of all tasks they've finished.

To count the task events, I've created a new metric

I have a dataset in Google Sheets that records updates to projects over time:

I'm using a tidyquery library in R to run SQL queries on my dataframe.
I'd like to keep the existing condition for Category but add a BETWEEN for end date i.e. Actual date is BETWEEN '2021-01-01' AND '2021-01-31'

How can I do this? Thanks. Edit: Original query

I am trying to count_distinct the invoice number from a table (using Google Sheets as data source). The invoice numbers may be numeric or alphanumeric. The problem is the count_distinct only counts numeric invoice numbers, while alphanumeric ones are not included in the count.

How can I fix this problem?

I am trying to implement the method that counts the number of distinct values in a queue. For example, if the queue looks like this: [1, 2, 2, 4, 4, 4, 8, 8, 10], then the method should return 5.

So I create the function like this:

I have a long column header that I would like to display on 2 lines instead of 1 in SQL SERVER.

Instead of the column header reading COUNT_DISTINCT_TRUCK_VIN, I would like to see

COUNT_DISTINCT
TRUCK_VIN

Another way to put it is that I would like to be able to wrap the text within the column header as one would in excel.

Is there any way to do this?

Thanks

I have a tasks in BigQuery with created date and last modified date. I would like to be able to report the number of task open and task close events by date in the same table if possible.