Refer to entire column in Access Query - ms-access

Question

I am trying to calculate the percentile of an entire column of data in an Access Query using a custom function that refers to the Excel Object Model. Here is the code I have:
Public Function myPercentile25(x As Double) As Double
myPercentile25 = Excel.WorksheetFunction.Percentile(x, 0.25)
End Function
I've added myPercentile25 function to the Query column in Design View where x equals AgedSalary using the following:
25P: myPercentile25([AgedSalary])
The issue I am having is the Query seems to be only taking the percentile for each individual row and not the entire column. I am more familiar with Excel where I would refer to column as AgedSalary:AgedSalary. Is there a similar syntax I can use in Access to take the percentile of the entire column?
Thank you.

Answer 1

It's easier to work with TOP in Access when you want a percentile:
select top 25 percent
[agedSalary]
from [yourTable]
order by [agedSalary];
The above query will return the top 25% of the records. If you want the top value (i.e. the 25 percentile) you can nest the above query:
select max([agedSalary) as percentile
from (
select top 25 percent [agedSalary]
from [yourTable]
order by [agedSalary])
) as a
If you want to do this using the design grid:
For the first query:
In the "Columns" area (the lower half of the design view), below each column, there's an "Order by" combo where you can select "Ascending" or "Descending"
You can set the TOP value in the property sheet of your query; in the Design ribbon click the "Property sheet" button
Once you are sure your query works (i.e. it selects the top 25% rows), you'll need to open the SQL view, cut the generated SELECT instruction and write this:
select a.*
from (
-- Paste HERE the SELECT you've just cut
) as a
Then return to the design grid, remove that * from the column grid and drag the desired field to the design view. Click on the Totals button in the Design ribbon (that big Sigma), and below the just dragged field, in the "Total" row select "Max"