SQL Server Group By Month

Question

我有一个具有此架构的表

ItemID    UserID    Year    IsPaid    PaymentDate  Amount
1         1         2009    0         2009-11-01  300
2         1         2009    0         2009-12-01  342
3         1         2010    0         2010-01-01  243
4         1         2010    0         2010-02-01  2543
5         1         2010    0         2010-03-01  475

我正在尝试查询工作,显示每个月的总计.到目前为止,我已经尝试过DateDiff和嵌套选择,但两者都没有给我我想要的东西.这是我认为最接近的:

DECLARE @start [datetime] = 2010/4/1;
SELECT ItemID, IsPaid,
(SELECT SUM(Amount) FROM Payments WHERE Year = 2010 And DateDiff(m, PaymentDate, @start) = 0 AND UserID = 100) AS "Apr",
(SELECT SUM(Amount) FROM Payments WHERE Year = 2010 AND DateDiff(m, PaymentDate, @start) =1 AND UserID = 100) AS "May",
(SELECT SUM(Amount) FROM Payments WHERE Year = 2010 AND DateDiff(m, PaymentDate, @start) =2 AND UserID = 100) AS "Jun", 
(SELECT SUM(Amount) FROM Payments WHERE Year = 2010 AND DateDiff(m, PaymentDate, @start) =3 AND UserID = 100) AS "Jul", 
(SELECT SUM(Amount) FROM Payments WHERE Year = 2010 AND DateDiff(m, PaymentDate, @start) =4  AND UserID = 100) AS "Aug", 
(SELECT SUM(Amount) FROM Payments WHERE Year = 2010 AND DateDiff(m, PaymentDate, @start) =5  AND UserID = 100) AS "Sep", 
(SELECT SUM(Amount) FROM Payments WHERE Year = 2010 AND DateDiff(m, PaymentDate, @start) =6  AND UserID = 100) AS "Oct", 
(SELECT SUM(Amount) FROM Payments WHERE Year = 2010 AND DateDiff(m, PaymentDate, @start) =7 AND UserID = 100) AS "Nov", 
(SELECT SUM(Amount) FROM Payments WHERE Year = 2010 AND DateDiff(m, PaymentDate, @start) =8 AND UserID = 100) AS "Dec", 
(SELECT SUM(Amount) FROM Payments WHERE Year = 2010 AND DateDiff(m, PaymentDate, @start) =9 AND UserID = 100) AS "Jan", 
(SELECT SUM(Amount) FROM Payments WHERE Year = 2010 AND DateDiff(m, PaymentDate, @start) =10 AND UserID = 100) AS "Feb", 
(SELECT SUM(Amount) FROM Payments WHERE Year = 2010 AND DateDiff(m, PaymentDate, @start) =11 AND UserID = 100) AS "Mar" 
FROM LIVE L INNER JOIN Payments I ON I.LiveID = L.RECORD_KEY 
WHERE UserID = 16178 

但是当我得到价值时,我只是得到空值.我错过了什么吗？

Answer 1

SELECT CONVERT(NVARCHAR(10), PaymentDate, 120) [Month], SUM(Amount) [TotalAmount]
FROM Payments
GROUP BY CONVERT(NVARCHAR(10), PaymentDate, 120)
ORDER BY [Month]

你也可以尝试:

SELECT DATEPART(Year, PaymentDate) Year, DATEPART(Month, PaymentDate) Month, SUM(Amount) [TotalAmount]
FROM Payments
GROUP BY DATEPART(Year, PaymentDate), DATEPART(Month, PaymentDate)
ORDER BY Year, Month

Answer 2

将NVARCHAR的尺寸限制为7,提供给CONVERT以仅显示"YYYY-MM"

SELECT CONVERT(NVARCHAR(7),PaymentDate,120) [Month], SUM(Amount) [TotalAmount]
FROM Payments
GROUP BY CONVERT(NVARCHAR(7),PaymentDate,120)
ORDER BY [Month]

Answer 3

我更喜欢这样的组合DATEADD和DATEDIFF功能:

GROUP BY DATEADD(MONTH, DATEDIFF(MONTH, 0, Created),0)

这两个函数一起将日期分量小于指定的datepart(即MONTH在此示例中).

您可以更改日期部分位YEAR,WEEK,DAY,等...这是超级方便.

您的原始SQL查询将看起来像这样(我无法测试它,因为我没有您的数据集,但它应该让您走在正确的轨道上).

DECLARE @start [datetime] = '2010-04-01';

SELECT
    ItemID,
    UserID,
    DATEADD(MONTH, DATEDIFF(MONTH, 0, Created),0) [Month],
    IsPaid,
    SUM(Amount)
FROM LIVE L
INNER JOIN Payments I ON I.LiveID = L.RECORD_KEY
WHERE UserID = 16178
AND PaymentDate > @start

还有一件事:如果您需要进一步处理该数据或将其映射到.NET对象,则Month列的类型DateTime也是一个很好的优势.