SQL：創建多個選擇基於一個日期

Question

我一直在尋找這方面的幫助，但我似乎無法找到解決方案。我擁有的是：

表名爲Details_Orders。 列：CustomerName，InvoiceDate，SaleAmount和SaleCost。

我想要做的是選擇日期（'1-1-2015'）並顯示客戶名稱，日期（'1-1-2015'），該日期的SaleAmount和SaleCost的總和。這裏是我遇到問題的部分，我希望下一列顯示前幾個月的SaleAmount和SaleCost，以及之前的SaleAmount和SaleCost。

我很難搞清楚如何編寫以前的時間段選擇語句。任何幫助，將不勝感激。

Select 
     CustomerName, 
     InvoiceDate, 
     Sum(SaleAmount), 
     Sum(SaleCost), 
     *PREVIOUS MONTH Sum(SalesAmount) DATEADD(MONTH,-1,'1-1'2015'), 
     PREVIOUS MONTH Sum(SalesCost) DATEADD(MONTH,-1,'1-1'2015'), 
     PREVIOUS YEAR Sum(SalesAmount) DATEADD(YEAR,-1,'1-1'2015'), 
     PREVIOUS YEAR Sum(SalesCost) DATEADD(YEAR,-1,'1-1'2015')* 
    From Details_Orders 
    WHERE InvoiceDate='1-1-2015' 

基本

Answer 1

你想使用條件聚集，還需要一個group by。上個月和下一年的確切定義有些不清楚。這裏有一個解釋：

Select CustomerName, 
      Sum(case when InvoiceDate = thedate then SaleAmount else 0 end), 
      Sum(case when InvoiceDate = thedate then SaleCost else 0 end), 
      Sum(case when year(InvoiceDate)*12 + month(InvoiceDate) = 
         year(thedate)*12 + month(thedate) - 1 
        then SaleAmount else 0 
       end), 
      Sum(case when year(InvoiceDate)*12 + month(InvoiceDate) = 
         year(thedate)*12 + month(thedate) - 1 
        then SaleCost else 0 
       end), 
      Sum(case when InvoiceDate < thedate and 
         InvoiceDate >= dateadd(year, -1, thedate 
        then SaleAmount else 0 
       end), 
      Sum(case when InvoiceDate < thedate and 
         InvoiceDate >= dateadd(year, -1, thedate 
        then SaleCost else 0 
       end) 
    From (select cast('2015-01-01' as date) as thedate 
     ) params cross join 
     Details_Orders o 
    group by CustomerName;