Transact-SQL Sub Query - sql

Question

I'm struggling to find the logic of how to accomplish a sub query, or at least that's what I think is required! I'll show what I have:
SELECT CH.SFA,
convert(datetime, RE.START_DATE, 103) AS 'START DATE',
Count(Distinct CH.CHNO) AS 'TOTAL CH',
Count(CH.STATUS) AS 'COMPLETED CH',
count(distinct CH.CHNO + CH.STATUS) As 'COMPLETED CH2'
FROM CUSTOMER.dbo. CH CH, CUSTOMER.dbo.RE RE
WHERE
RE.SFA = CH.SFA
GROUP BY
CH.SFA, RE.START_DATE
What I am trying to do is where I have COMPLETED CH2 I need to specify that it ends with a C, the Status Column is either blanks or C's and by doing a distinct count of CHNO and C together give me the result I need but I cannot for the life of me find out how to write it!
I am using Microsoft Query to take the data from its source straight into the Excel spreadsheet.
Many thanks for taking a look.

Answer 1

Been ages since I've used MS Query so I'm fuzzy on syntax, but this is the general idea of how to write a subquery containing a WHERE clause and an aggregation to get you started:
SELECT
CH.SFA,
convert(datetime, RE.START_DATE, 103) AS 'START DATE',
Count(DISTINCT CH.CHNO) AS 'TOTAL CH',
Count(CH.STATUS) AS 'COMPLETED CH',
CCH.COMPLETED_CH2 AS 'COMPLETED CH2'
FROM CUSTOMER.dbo.CH CH
INNER JOIN CUSTOMER.dbo.RE RE
ON RE.SFA = CH.SFA
LEFT JOIN (
SELECT SFA, COUNT(DISTINCT CH.CHNO) AS COMPLETED_CH2
FROM CUSTOMER.dbo.CH
WHERE STATUS = 'C'
GROUP BY SFA
) AS CCH
ON RE.SFA = CCH.SFA
GROUP BY CH.SFA, RE.START_DATE

Answer 2

if you just want to know count of records where CH.STATUS = 'C' than add another COUNT statement with CASE logic.
COUNT(CASE WHEN CH.STATUS = 'C' then 1 else null end) as 'COMPLETED CH2'
when combining COUNT and CASE statement remember to have NULL for ELSE statement, otherwise all rows will be counted.
as an alternative you can do it with a SUM
SUM(CASE WHEN CH.STATUS = 'C' then 1 else 0 end) as 'COMPLETED CH2'