Is it possible to select a column from a database and not display it in the result set - if selected, causes an issue with Group By - sql

Question

I have a query that's being use in my application. I had to make a small edit to it (select an additional column) and now that I do that, I don't get the same results, therefore I get a bad file. Just to give example this is what the query looks like ....
Select
'X' = tblA.VendorNumber,
'Y' = tblB.Label,
'Z' = tblC.InvoiceNo,
'W' = tblD.Checks,
From //Doing some joins here
Group By
tblA.VendorNumber, tblB.label, tblc.InvoiceNo, tblD.Checks
The result set gives me many records, but groups by the ones with identical X,Y,Z,W - so with no Group By it would look like this
X Y Z W
-----------------------------------------------------------
123 Anton 772 0
123 Anton 772 0
Obviously, with the group by they are rolled up into one...
The issue comes when I try to include an additional column in my Select query. I need this query in my, because I need to value in my code to be able to distinguish what type of record it is. With the new column, these two rows of data are not the same, therefore they do not get rolled up.
Is there a way for me to somehow add an additional column, but not display it, and exclude it from the Group By?
This is what I mean
Select
'X' = tblA.VendorNumber,
'Y' = tblB.Label,
'Z' = tblC.InvoiceNo,
'W' = tblD.Checks,
'P' = tblC.Proc -- New column
From //Doing some joins here
Group By
tblA.VendorNumber, tblB.label, tblc.InvoiceNo, tblD.Checks,
tblC.Proc -- New column
In this case the data looks like this
X Y Z W P
---------------------------------------------------------------------
123 Anton 772 0 FPN
123 Anton 772 0 PPN
So now that P is different for the 2 records that previously were rolled up into one, is there a way for me to somehow not display P, however, still be able to get it's value from my record set. I am unable to select the 'P' if it's not selected in this one query and because of the fact that the two records are not rolling up, I'm having some major issues.
Basically I need to select 'P' but not include it in my result set or group by.
Any help would be much appreciated.

Answer 1

There's a couple of options, I guess... There's not really a way to get values without having them in your results. How else would you read them?
One would be to STUFF the values of 'P' into a comma delimited list ie:
X Y Z W P
123 Anton 772 0 FPN,PPN
Then read them in your application separated by comma. Read here: https://stackoverflow.com/questions/31211506/how-stuff-and-for-xml-path-work-in-sql-server
Another would be to create boolean headers if there's not too many options for 'P' or you know all of the options. You can create them using CASE statements like:
,SUM(CASE WHEN tlbc.Proc = 'PPN' THEN 1 ELSE 0 END) AS "PPN"
EDIT: Left out an aggregate around it so it groups correctly. Can use MAX, for 1 or 0, as well... depends how many results there can be for tlbc.Proc. Some aggregate function around your cases will combine your rows to one.
For results like:
X Y Z W FPN PPN AnotherP
123 Anton 772 0 1 1 0
Third, if I misread your question and you don't need the values but just need them in a WHERE, then don't display them.
There's definitely more ways to go about this.
Does this help?

Answer 2

You need to do some sort of aggregate function on P so you don't need to group on it. If you only care about one of the values, you could use MIN() or MAX() to get one of them.
So, something like:
SELECT X, Y, Z, MAX(P) AS P etc....
Another way would be to use something like FOR XML PATH to pivot the values into a single value (maybe a comma separated list). There are lots of examples online of people doing this. Here is one example:
https://sqlperformance.com/2014/08/t-sql-queries/sql-server-grouped-concatenation

Answer 3

If you only want one record per first DISTINCT four column, which one of the P column you want to show?
If you have an answer for this question, just add to the query
Where tblC.Proc = -->YOUR_EXPECTED_VALUE_OR_CONDITION_HERE<--