Arithmetic overflow error converting varchar to data type numeric CASE statement

Question

I am trying to write a query that returns an "Estimated Annual Value", and for this, I am using a Case statement. There are two inner joins involved in the query.

So, the query and gives me result when I am running this piece:

select Users.Id, Name, PhoneNumber, Email, Currency, count(*) as TotalOrders, sum(TotalCustomerAmount) as TotalOrderValue, avg(TotalCustomerAmount) as AverageOrderValue, TsCreate as RegistrationDate, max(TsOrderPlaced) as LastOrderDate, min(TsOrderPlaced) as FirstOrderDate, 
CASE 
    When PromotionsEnabled = 0 then 'Y'
    When PromotionsEnabled = 1 then 'n'
    else 'undefined'
end as Promotions,
/*CASE
    When ((DATEDIFF(day, max(TsOrderPlaced), min(TsOrderPlaced)) >= 6) AND (count(*) > 3)) then  ((sum(TotalCustomerAmount)/(DATEDIFF(day, max(TsOrderPlaced), min(TsOrderPlaced))))*365) 
    Else '-'
end as EstimatedAnnualValue*/
from AspNetUsers with (nolock)
    inner join Orders with (nolock) on Orders.UserId = AspNetUsers.Id and Orders.WhiteLabelConfigId = @WhiteLabelConfigId
                                    and Orders.OrderState in (2,3,4,12)     
    inner join UserWhiteLabelConfigs with (nolock) on UserWhiteLabelConfigs.UserId = AspNetUsers.Id and Orders.WhiteLabelConfigId = @WhiteLabelConfigId
where AspNetUsers.Discriminator = 'ApplicationUser'
group by Users.Id, Name, Number, Currency, Email, TsCreate, PromotionsEnabled

But the problem comes when I am running this with the second CSAE statement, is it because I cannot use the aggregate function before GROUP BY? I am also thinking of using a Subquery Looking fr some help!!

Answer 1

You need to use aggregation functions. For instance, if you want 'Y' only when all values are 0 or NULL :

(case when max(PromotionsEnabled) = 0 then 'Y'
      when max(PromotionsEnabled) = 1 then 'N'
      else 'undefined'
 end) as Promotions,

I'm not sure if this is the logic you want (because that detail is not in the question). However, this shows that you can use aggregation functions in a case expression .