Divide by Case When - sql

Question

I'm currently doing some work on a 6 month rolling report, but i seem to be a little bit stuck on one area.
I have one column Liveatcutoff_PC it will be populated by 1 for live or 0 for not live. If it's 0 it means it's cancelled. I want to work out the cancellation % for the date range in my code but I'm not having much luck.
SELECT
UserID
,Agent
,COUNT(CASE WHEN SaleDate>=DATEADD(MONTH, DATEDIFF(MONTH, 0, GETDATE())-6, 0)
AND SaleDate < DATEADD(MONTH, DATEDIFF(MONTH, -6, GETDATE())-6, 0)
AND LiveAtCutOff_PC='0' THEN LiveAtCutOff_PC END)
FROM PDS_SALES_PMI
WHERE SaleDate>='2019-01-01'
AND Leaver='0'
GROUP BY UserID, Agent
Help much appreciated.

Answer 1

If I understand correctly, you can use AVG():
AVG(CASE WHEN SaleDate >= DATEADD(MONTH, DATEDIFF(MONTH, 0, GETDATE())-6, 0) AND
SaleDate < DATEADD(MONTH, DATEDIFF(MONTH, -6, GETDATE())-6, 0) THEN LiveAtCutOff_PC * 1.0
END) as LiveAtCutoff_PC_ratio
Your question specifies that LiveAtCutOff_PC has values of 0 and 1, which implies that the field is a number. However, the code compares it to a string, which suggests otherwise. If the values are only 0 and 1 then the above should work for both numbers and strings (although for bit you would need to convert the value).

Answer 2

So since you requirement is to find out the percentage of canceled sales then you don't have to do it in one query. Case will just calculate everything, including nulls(that will come up because you don't have 'else')
you might want to try subquery instead or use CTE.
CTE example
with CTE as (
Select UserID
,Agent
,COUNT(*) as Canceled
from PDS_SALES_PMI
where SaleDate >=DATEADD(MONTH, DATEDIFF(MONTH, 0, GETDATE())-6, 0)
AND SaleDate < DATEADD(MONTH, DATEDIFF(MONTH, -6, GETDATE())-6, 0)
AND LiveAtCutOff_PC='0'
AND SaleDate >='2019-01-01'
AND Leaver = 0
group by UserID, AgentID)
Select a.UserID
,a.AgentID
,Canceled/COUNT(*) * 100.0 as Canceled_Percent
From PDS_SALES_PMI a INNER JOIN CTE
on a.AgentID = CTE.AgentID
and a.UserID = CTE.UserID
Where SaleDate >=DATEADD(MONTH, DATEDIFF(MONTH, 0, GETDATE())-6, 0)
AND SaleDate < DATEADD(MONTH, DATEDIFF(MONTH, -6, GETDATE())-6, 0)
AND SaleDate >='2019-01-01'
AND Leaver = 0
Group by a.UserID, a.AgentID
Subquery Example
Select a.UserID
,a.AgentID
,Canceled/COUNT(*) * 100.0 as Canceled_Percent
From PDS_SALES_PMI a INNER JOIN (
Select UserID
,Agent
,COUNT(*) as Canceled
from PDS_SALES_PMI
where SaleDate >=DATEADD(MONTH, DATEDIFF(MONTH, 0,GETDATE())-6, 0)
AND SaleDate < DATEADD(MONTH, DATEDIFF(MONTH, -6, GETDATE())-6, 0)
AND LiveAtCutOff_PC='0'
AND SaleDate >='2019-01-01'
AND Leaver = 0
group by UserID, AgentID) as Tmp
on a.AgentID = Tmp.AgentID
and a.UserID = Tmp.UserID
Where SaleDate >=DATEADD(MONTH, DATEDIFF(MONTH, 0, GETDATE())-6, 0)
AND SaleDate < DATEADD(MONTH, DATEDIFF(MONTH, -6, GETDATE())-6, 0)
AND SaleDate >='2019-01-01'
AND Leaver = 0
Group by a.UserID, a.AgentID