Find the Same day of Previous Year Given by Current Year Date in SQL Server - sql

Question

I am working with SQL Server, The scenario is to find out the Same Day's Date of Previous Year as of Today's Day.
Suppose 2014-03-06 is Today Date and Day is Thursday I want to Find the Same day in Previous lies in the same week .which is 2013-03-07
can any body help?
HERE is what i Have Written:
DECLARE #DateFrom AS DATETIME
DECLARE #DateTo AS DATETIME
SET #DateFrom = '2014-01-01'
SET #DateTo = '2014-02-10'
DECLARE #Count AS INT
SET #Count = DATEDIFF(DAY, #DateFrom, #DateTo)
CREATE TABLE #current_year /*This Year*/
(
[Date] DATETIME ,
WeekNum INT,
[Day] VARCHAR(20),
Data INT
)
CREATE TABLE #last_year /*This Year -1*/
(
[Date] DATETIME ,
WeekNum INT,
[Day] VARCHAR(20),
Data INT
)
WHILE ( #Count > 0 )
BEGIN
INSERT INTO #current_year
VALUES ( CONVERT(VARCHAR(10), #DateFrom, 101),
DATEPART(week,#DateFrom),
DATENAME(weekday, #DateFrom),#Count)
INSERT INTO #last_year
VALUES ( CONVERT(VARCHAR(10), DATEADD(YEAR, -1, #DateFrom), 101),
DATEPART(week,DATEADD(YEAR,1,#DateFrom)),
DATENAME(weekday, DATEADD(YEAR, -1, #DateFrom)),#Count)
SET #DateFrom = DATEADD(day, 1, #DateFrom)
SET #Count = #Count - 1
END
SELECT * from #current_year
SELECT * from #last_year
SELECT CONVERT(varchar(10),#current_year.[Date],111) AS CYDate,
--ISNULL(CONVERT(varchar(10),#last_year.[Date],111) ,/*CONVERT(varchar(10),DateAdd(dd, 1, DATEADD(yy, -1, #current_year.Date)),111)*/) AS LYDate
--CONVERT(varchar(10),#last_year.[Date],111) AS LYDate
Coalesce(CONVERT(varchar(10),#last_year.[Date],111) ,DateAdd(dd, 1, DATEADD(yy, -1, #current_year.Date))) AS LYDate,
#current_year.Data AS CD,
#last_year.Data AS LD
FROM #current_year
--LEFT JOIN #last_year ON #last_year.WeekNum = #current_year.WeekNum
-- AND #last_year.[Day] = #current_year.[Day]
Left JOIN #last_year ON #last_year.WeekNum = DatePart(wk, GETDATE())
DROP TABLE #current_year
DROP TABLE #last_year
Here is the Output:
Here is the output after adding your solution, now in left join it excludes (NULL) data of previous year

Answer 1

Basically you need to find difference in days between same dates in this and previous years, then understand "day difference" by mod 7, and sum it with date in previous year:
DECLARE #now DATETIME
SET #now = '2014-03-06'
SELECT CAST (DATEADD(YEAR, -1, #now) + (CAST (#now as INT) - CAST (DATEADD(YEAR, -1, #now) AS INT)) % 7 AS DATE)
Returns
2013-03-07

Answer 2

Try
DECLARE #now Date
SET #now = '2014-06-03'
SELECT DATEADD(week, -52, #now)

Answer 3

SELECT DateName(dw, DATEADD(yy, -1, GETDATE()))
gives Wednesday
SELECT DateName(dw, DateAdd(dd, 1, DATEADD(yy, -1, GETDATE())))
gives Thursday
edit:
SELECT DateAdd(dd, 1, DATEADD(yy, -1, GETDATE()))
gives '2013-03-07 17:30:16.590'
you need to cast the date as per you requirement..
update:
change this part with,
Left JOIN #last_year ON #last_year.WeekNum = DatePart(wk, GETDATE())
in your case:
Left JOIN #last_year ON DatePart(wk, #last_year.[Date]) = DatePart(wk, #current_year.[Date])
update 2:
Left JOIN #last_year ON (MONTH(#last_year.[Date])=MONTH(#current_year.[Date]) and Day(#last_year.[Date])=Day(#current_year.[Date]))
Output:
or
output:
Left JOIN #last_year ON (#last_year.WeekNum = #current_year.WeekNum and #last_year.[Day] = #current_year.[Day])
choose which ever is your required output.

Answer 4

DECLARE #Date DATE = '2014-03-06'
SELECT DATEADD(WEEK,-52,#Date)
Retrun value :
2013-03-07