将 varchar 转换为数据类型 numeric CASE 语句的算术溢出错误

Question

我正在尝试编写一个返回“估计年值”的查询，为此，我使用了 Case 语句。 查询中涉及两个内部联接。

因此，当我运行这件作品时，查询并给出了结果：

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

但是当我使用第二个 CSAE 语句运行它时出现问题，是因为我不能在 GROUP BY 之前使用聚合 function 吗？ 我也在考虑使用子查询寻找一些帮助！

Answer 1

您需要使用聚合函数。 例如，如果您仅在所有值为0或NULL时才需要'Y' ：

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

我不确定这是否是您想要的逻辑（因为该细节不在问题中）。 但是，这表明您可以在case表达式中使用聚合函数。