Isso pressupõe valores crescentes de ID e lidará com lacunas no ID
SELECT
ID,
This.Number AS CurrentValue,
Prev2.Number AS PreviousValue
FROM
myTable This
OUTER APPLY
(
SELECT TOP 1
Number
FROM
myTable Prev
WHERE
Prev.ID < This.ID -- change to number if you want
ORDER BY
Prev.ID DESC
) Prev2;
OU
WITH CTE
AS (SELECT ID,
Number,
ROW_NUMBER() OVER (ORDER BY ID) AS rn
FROM Mytable)
SELECT ID,
This.Number AS CurrentValue,
Prev.Number AS PreviousValue
FROM CTE This
LEFT JOIN CTE Prev
ON Prev.rn + 1 = This.rn;
E para o SQL Server 2012
SELECT
ID,
Number AS CurrentValue,
LAG(Number) OVER (ORDER BY ID) AS PreviousValue
FROM
MyTable