我有一张桌子MonthlyShipments
看起来像:
partnumber | quantity | month | year |
part1 | 12 | 6 | 2011 |
part1 | 22 | 5 | 2011 |
part1 | 32 | 4 | 2011 |
part1 | 42 | 3 | 2011 |
part1 | 52 | 2 | 2011 |
我想对过去 3 个月的数量求和,不包括当月。我的 where 子句目前如下所示:
where
MonthlyShipments.Month <> MONTH(GETDATE()) AND
CAST(
(CAST(MonthlyShipments.Month as nvarchar(2)) +
'-01-' +
CAST(MonthlyShipments.Year as nvarchar(4))) as DateTime)
> DATEADD(m, -4, GETDATE())
它有效,但它丑陋且侮辱性。有什么建议可以让它变得更漂亮吗?非常感谢!
好不了多少...
DATEDIFF(
month,
DATEADD(Year, MonthlyShipments.Year-1900,
DATEADD(Month, MonthlyShipments.Month-1, 0)
),
GETDATE()
) BETWEEN 1 AND 3
但是嵌套的 DATEADD 可以成为计算列和索引列
ALTER TABLE MonthlyShipments ADD
ShipDate AS DATEADD(Year, MonthlyShipments.Year-1900,
DATEADD(Month, MonthlyShipments.Month-1, 0)
)
这使
WHERE DATEDIFF(month, ShipDate, GETDATE()) BETWEEN 1 AND 3
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