SQL查找上一行和当前行之间的差异

Question

我试图找到当前行和上一行之间的差异.但是,我收到以下错误消息:

无法绑定多部分标识符"tableName".

不确定如何修复错误.

谢谢!

输出应如下所示:

columnOfNumbers     Difference
      1               NULL
      2               1
      3               1
      10              7
      12              2
      ....            ....

码:

USE DATABASE;

WITH CTE AS 
(SELECT 
    ROW_NUMBER() OVER (PARTITION BY tableName ORDER BY columnOfNumbers) ROW,
    columnOfNumbers
    FROM tableName)
SELECT
    a.columnOfNumbers
FROM
    CTE a
    LEFT JOIN CTE b
    ON a.columnOfNumbers = b.columnOfNumbers AND a.ROW = b.ROW + 1

Answer 1

如果您使用的是SQL Server 2012+,则可以使用LAG.

 SELECT columnOfNumbers
       ,columnOfNumbers - LAG(columnOfNumbers, 1) OVER (ORDER BY columnOfNumbers)
   FROM tableName

注意:LAG的可选第三个参数是:

默认

当偏移处的scalar_expression为NULL时返回的值.如果未指定默认值,则返回NULL.default可以是列,子查询或其他表达式,但它不能是分析函数.default必须与scalar_expression类型兼容.

Answer 2

见sqlFiddle

;WITH tblDifference AS
(
    SELECT ROW_NUMBER() OVER(ORDER BY id) AS RowNumber, columnOfNumbers 
    FROM tableName
)

SELECT cur.columnOfNumbers, cur.columnOfNumbers - previous.columnOfNumbers
FROM tblDifference cur
LEFT OUTER JOIN tblDifference previous
ON cur.RowNumber = previous.RowNumber + 1