Question

我正在尝试计算前几个月的发票金额，并将其与当前值放在同一行。

我使用的是SQL Server.Microsoft SQL Server 2008 R2（SP2）

我已经尝试过使用CTE和所有奇怪的连接，但我的输出永远不正确。有人能指出我正确的方向吗？

示例表：

invoice_month   value
--------------------------
    201510      337265.386
    201511      335466.456
    201512      338646.500
    201601      333440.380
    201602      330731.208
    201603      339299.752
    201604      340878.168
    201605      359585.382
    201606      339616.430
    201607      316457.486
    201608      308009.976
    201609      232196.268
    201610      894839.180
    201611      232196.268
    201612      232196.268
    201701      232196.268
    201702      232196.268
    201703      232196.268

预期输出为：

invoice_month   value,         prevValue
--------------------------------------------
    201510      337265.386,    NULL
    201511      335466.456,    337265.386
    201512      338646.500,    335466.456
    201601      333440.380,    333440.380
    201602      330731.208,    333440.380
    201603      339299.752,    330731.208
    201604      340878.168,    339299.752
    201605      359585.382,    340878.168
    201606      339616.430,    359585.382
    201607      316457.486,    339616.430
    201608      308009.976,    316457.486
    201609      232196.268,    308009.976
    201610      894839.180,    232196.268
    201611      232196.268,    894839.180
    201612      232196.268,    232196.268
    201701      232196.268,    232196.268
    201702      232196.268,    232196.268
    201703      232196.268,    232196.268

Answer 1

在SQL Server 2012+中，您将使用lag()：

select t.invoice_month, t.value,
       lag(t.value) over (order by t.invoice_month) as prev_value
from t;

这是ANSI标准功能。在早期版本的SQL Server中，还有其他方法。

Answer 2

对于2012年之前的版本

：

;with cte
 as
(select invoice_month,value,
row_number() over (order by invoice_month) as rn
from  #temp  )
select c1.*,c2.value
from cte c1
left join
cte c2
on c1.rn=c2.rn+1

Answer 3

SELECT *
FROM   (SELECT TOP 1 invoice_month,
                     value,
                     NULL AS [Previous value]
        FROM   Invoice
        ORDER  BY invoice_month ASC) T
UNION
SELECT I.invoice_month,
       I.value,
       I1.value AS [Previous value]
FROM   Invoice I
       INNER JOIN Invoice I1
               ON I.invoice_month - 1 = I1.invoice_month

根据上面的SQL计算

3 个答案: