How do you get positive and negative rows based on date - tsql

Question

I'm trying to get ordinance by the current date from a table. this query does what I want but it seems overkill:
WITH dates
AS (SELECT Month,
FQ,
FY,
MonthDisplay,
CAST (datepart(yyyy, [Month]) AS VARCHAR) + '-' + RIGHT(CAST ((datepart(MM, [Month]) + 100) AS VARCHAR), 2) AS YM,
fh,
LEFT(CONVERT (VARCHAR, [Month], 100), 3) + ' ' + RIGHT(fy, 4) AS MY,
LEFT(CONVERT (VARCHAR, [Month], 100), 3) AS ShortMonthName
FROM Pipeline.DimTime AS dt),
datesafter
AS (SELECT dt.FH,
dt.FQ,
dt.FY,
dt.MY,
dt.Month,
dt.MonthDisplay,
dt.ShortMonthName,
dt.YM,
ROW_NUMBER() OVER ( ORDER BY [Month]) AS RowNum
FROM dates AS dt
WHERE dt.[Month] >= (SELECT TOP 1 DATEADD(MONTH, DATEDIFF(MONTH, 0, ds.SnapshotDate), 0)
FROM dbo.vw_DimSnapshot AS ds
WHERE ds.SnapshotWeek = 'Current')),
datesbefore
AS (SELECT dt.FH,
dt.FQ,
dt.FY,
dt.MY,
dt.Month,
dt.MonthDisplay,
dt.ShortMonthName,
dt.YM,
(ROW_NUMBER() OVER ( ORDER BY [Month] DESC)) * -1 AS RowNum
FROM dates AS dt
WHERE dt.[Month] < (SELECT TOP 1 DATEADD(MONTH, DATEDIFF(MONTH, 0, ds.SnapshotDate), 0)
FROM dbo.vw_DimSnapshot AS ds
WHERE ds.SnapshotWeek = 'Current'))
SELECT *
FROM datesafter
UNION ALL
SELECT *
FROM datesbefore
ORDER BY [month];

Answer 1

I think you can do it in a single query by using datediff. Pass current date as one parameter and the table date as another. This will work if you are ok with skipping missing dates. For example if current date is Nov 21, then Nov 20 will show up as -1 and Nov 18 will show up as -3 even if Nov 19 is missing in the data. I am not sure what your business requirement is, so cannot comment beyond that.
And by the way if you are looking for ordinance based on months instead of day, you can use still use datediff but use the correct datepart (See: http://msdn.microsoft.com/en-us/library/ms189794.aspx).
HTH.
-Tabrez