选择年度报告的记录(过去3年)

Question

考虑以下SQL语句：

DECLARE @CustomerId INT = 48;
DECLARE @CurrentYear INT = DATEPART(YEAR, GETDATE());

SELECT
    YEAR(o.OrderDate) AS Year,
    0 AS Month,
    SUM(o.GrandTotal) AS GrandTotal
FROM [Order] o
WHERE
    o.CustomerId = @CustomerId AND
    o.OrderTypeId = 4 AND
    o.IsVoid = 0 AND
    YEAR(o.OrderDate) BETWEEN @CurrentYear - 2 AND @CurrentYear
GROUP BY
    YEAR(o.OrderDate)

它正确地产生结果：

2012, 0, 89.00
2011, 0, 230.00
2010, 0, 450.0

但是，如果另一个客户仅为2011年下了订单，我需要生成这2行(尽管值为0)：

2011, 0, 230.00
2012, 0, 0
2010, 0, 0

我应该怎样才能正确地做到这一点呢？请注意，这份报告将在过去三年内编写。

第4次更新I按建议修改了代码：

DECLARE @CustomerId INT = 48;
DECLARE @CurrentYear INT = YEAR(GETDATE());

DECLARE @years TABLE (
    yr INT
);
INSERT INTO @years VALUES
    (@CurrentYear),
    (@CurrentYear - 1),
    (@CurrentYear - 2)

这会产生如下结果集(我已经检查过，并确保是这样的)。

2012
2011
2010

然后，我按如下方式加入表(右联接)：

SELECT
    y.yr AS Year,
    0 AS Month,
    SUM(ISNULL(o.GrandTotal, 0)) AS GrandTotal
FROM [Order] o
RIGHT JOIN @years y ON y.yr = YEAR(o.OrderDate)
WHERE
    o.CustomerId = @CustomerId AND
    o.OrderTypeId = 4 AND
    o.IsVoid = 0
GROUP BY
    y.yr

但是，考虑到客户还没有下订单，所以这需要生成3行零值。然而，所建议的解决办法中没有一个能做到这一点。

最终更新解决了where子句阻止这些行在最终结果集中的问题。因此，正如达文所建议的，我只是把WHERE子句替换为AND，问题就解决了。

SELECT
    y.yr AS Year,
    0 AS Month,
    SUM(ISNULL(o.GrandTotal, 0)) AS GrandTotal
FROM [Order] o
RIGHT JOIN @years y ON y.yr = YEAR(o.OrderDate) AND
    o.CustomerId = @CustomerId AND
    o.OrderTypeId = 4 AND
    o.IsVoid = 0
GROUP BY
    y.yr

Answer 1

以下几点如何？

DECLARE @CustomerId INT = 48; 
DECLARE @CurrentYear INT = DATEPART(YEAR, GETDATE());  

;with years as 
( 
SELECT YEAR(GETDATE()) as yr 
UNION ALL SELECT YEAR(DATEADD(YY,-1,GETDATE())) 
UNION ALL SELECT YEAR(DATEADD(YY,-2,GETDATE())) 
) 
SELECT      
years.yr 
,0 AS Month 
,SUM(ISNULL(o.GrandTotal,0)) AS GrandTotal  
FROM years 
LEFT OUTER JOIN Order o  
ON YEAR(o.OrderDate) = years.yr 
AND o.customerid = @customerid
AND     o.OrderTypeId = 4  
AND     o.IsVoid = 0  
GROUP BY      
years.yr 

Answer 2

我用小提琴写了示例代码。希望http://sqlfiddle.com/#!3/eddfe/9/0能帮上忙。

这样做的想法是创建一个包含所有年份的UDF，然后对该表执行外部连接。