Solution
The date format that you requested is called ODBC format (code 120).
To actually calculate the values that you requested, include the following in your SQL.
Copy, paste...
DECLARE
@FirstDayOfLastMonth DATETIME = CONVERT(DATE, DATEADD(d, -( DAY(DATEADD(m, -1, GETDATE() - 2)) ), DATEADD(m, -1, GETDATE() - 1)))
, @LastDayOfLastMonth DATETIME = CONVERT(DATE, DATEADD(d, -( DAY(GETDATE()) ), GETDATE()))
...and use in your code:
- @FirstDayOfLastMonth
- @LastDayOfLastMonth
Be aware that it has to be pasted earlier than any statements that reference the parameters, but from that point on you can reference @FirstDayOfLastMonth and @LastDayOfLastMonth in your code.
Example
Let's see some code in action:
DECLARE
@FirstDayOfLastMonth DATETIME = CONVERT(DATE, DATEADD(d, -( DAY(DATEADD(m, -1, GETDATE() - 2)) ), DATEADD(m, -1, GETDATE() - 1)))
, @LastDayOfLastMonth DATETIME = CONVERT(DATE, DATEADD(d, -( DAY(GETDATE()) ), GETDATE()))
SELECT
'First day of last month' AS Title, CONVERT(VARCHAR, @FirstDayOfLastMonth , 120) AS [ODBC]
UNION
SELECT
'Last day of last month' AS Title, CONVERT(VARCHAR, @LastDayOfLastMonth , 120) AS [ODBC]
Run the above code to produce the following output:

Note: Bear in mind that today's date for me is 12th September, 2016.
More (for completeness' sake)
Common date parameters
Are you left wanting more?
To set up a more comprehensive range of handy date related parameters, include the following in your SQL:
DECLARE
@FirstDayOfCurrentWeek DATETIME = CONVERT(DATE, DATEADD(WEEK, DATEDIFF(WEEK, 0, GETDATE()), 0))
, @LastDayOfCurrentWeek DATETIME = CONVERT(DATE, DATEADD(WEEK, DATEDIFF(WEEK, 0, GETDATE()), 6))
, @FirstDayOfLastWeek DATETIME = CONVERT(DATE, DATEADD(WEEK, DATEDIFF(WEEK, 7, GETDATE()), 0))
, @LastDayOfLastWeek DATETIME = CONVERT(DATE, DATEADD(WEEK, DATEDIFF(WEEK, 7, GETDATE()), 6))
, @FirstDayOfNextWeek DATETIME = CONVERT(DATE, DATEADD(WEEK, DATEDIFF(WEEK, 0, GETDATE()), 7))
, @LastDayOfNextWeek DATETIME = CONVERT(DATE, DATEADD(WEEK, DATEDIFF(WEEK, 0, GETDATE()), 13))
, @FirstDayOfCurrentMonth DATETIME = CONVERT(DATE, DATEADD(d, -( DAY(GETDATE() - 1) ), GETDATE()))
, @LastDayOfCurrentMonth DATETIME = CONVERT(DATE, DATEADD(d, -( DAY(DATEADD(m, 1, GETDATE())) ), DATEADD(m, 1, GETDATE())))
, @FirstDayOfLastMonth DATETIME = CONVERT(DATE, DATEADD(d, -( DAY(DATEADD(m, -1, GETDATE() - 2)) ), DATEADD(m, -1, GETDATE() - 1)))
, @LastDayOfLastMonth DATETIME = CONVERT(DATE, DATEADD(d, -( DAY(GETDATE()) ), GETDATE()))
, @FirstDayOfNextMonth DATETIME = CONVERT(DATE, DATEADD(d, -( DAY(DATEADD(m, 1, GETDATE() - 1)) ), DATEADD(m, 1, GETDATE())))
, @LastDayOfNextMonth DATETIME = CONVERT(DATE, DATEADD(d, -( DAY(DATEADD(m, 2, GETDATE())) ), DATEADD(m, 2, GETDATE())))
, @FirstDayOfCurrentYear DATETIME = CONVERT(DATE, DATEADD(YEAR, DATEDIFF(YEAR, 0, GETDATE()), 0))
, @LastDayOfCurrentYear DATETIME = CONVERT(DATE, DATEADD(ms, -2, DATEADD(YEAR, 0, DATEADD(YEAR, DATEDIFF(YEAR, 0, GETDATE()) + 1, 0))))
, @FirstDayOfLastYear DATETIME = CONVERT(DATE, DATEADD(YEAR, DATEDIFF(YEAR, 0, GETDATE()) - 1, 0))
, @LastDayOfLastYear DATETIME = CONVERT(DATE, DATEADD(ms, -2, DATEADD(YEAR, 0, DATEADD(YEAR, DATEDIFF(YEAR, 0, GETDATE()), 0))))
, @FirstDayOfNextYear DATETIME = CONVERT(DATE, DATEADD(YEAR, DATEDIFF(YEAR, 0, GETDATE()) + 1, 0))
, @LastDayOfNextYear DATETIME = CONVERT(DATE, DATEADD(ms, -2, DATEADD(YEAR, 0, DATEADD(YEAR, DATEDIFF(YEAR, 0, GETDATE()) + 2, 0))))
It would make most sense to include it earlier on, preferably at the top of your procedure or SQL query.
Once declared, the parameters can be referenced anywhere in your code, as many times as you need them.
Example
Let's see some code in action:
DECLARE
@FirstDayOfCurrentWeek DATETIME = CONVERT(DATE, DATEADD(WEEK, DATEDIFF(WEEK, 0, GETDATE()), 0))
, @LastDayOfCurrentWeek DATETIME = CONVERT(DATE, DATEADD(WEEK, DATEDIFF(WEEK, 0, GETDATE()), 6))
, @FirstDayOfLastWeek DATETIME = CONVERT(DATE, DATEADD(WEEK, DATEDIFF(WEEK, 7, GETDATE()), 0))
, @LastDayOfLastWeek DATETIME = CONVERT(DATE, DATEADD(WEEK, DATEDIFF(WEEK, 7, GETDATE()), 6))
, @FirstDayOfNextWeek DATETIME = CONVERT(DATE, DATEADD(WEEK, DATEDIFF(WEEK, 0, GETDATE()), 7))
, @LastDayOfNextWeek DATETIME = CONVERT(DATE, DATEADD(WEEK, DATEDIFF(WEEK, 0, GETDATE()), 13))
, @FirstDayOfCurrentMonth DATETIME = CONVERT(DATE, DATEADD(d, -( DAY(GETDATE() - 1) ), GETDATE()))
, @LastDayOfCurrentMonth DATETIME = CONVERT(DATE, DATEADD(d, -( DAY(DATEADD(m, 1, GETDATE())) ), DATEADD(m, 1, GETDATE())))
, @FirstDayOfLastMonth DATETIME = CONVERT(DATE, DATEADD(d, -( DAY(DATEADD(m, -1, GETDATE() - 2)) ), DATEADD(m, -1, GETDATE() - 1)))
, @LastDayOfLastMonth DATETIME = CONVERT(DATE, DATEADD(d, -( DAY(GETDATE()) ), GETDATE()))
, @FirstDayOfNextMonth DATETIME = CONVERT(DATE, DATEADD(d, -( DAY(DATEADD(m, 1, GETDATE() - 1)) ), DATEADD(m, 1, GETDATE())))
, @LastDayOfNextMonth DATETIME = CONVERT(DATE, DATEADD(d, -( DAY(DATEADD(m, 2, GETDATE())) ), DATEADD(m, 2, GETDATE())))
, @FirstDayOfCurrentYear DATETIME = CONVERT(DATE, DATEADD(YEAR, DATEDIFF(YEAR, 0, GETDATE()), 0))
, @LastDayOfCurrentYear DATETIME = CONVERT(DATE, DATEADD(ms, -2, DATEADD(YEAR, 0, DATEADD(YEAR, DATEDIFF(YEAR, 0, GETDATE()) + 1, 0))))
, @FirstDayOfLastYear DATETIME = CONVERT(DATE, DATEADD(YEAR, DATEDIFF(YEAR, 0, GETDATE()) - 1, 0))
, @LastDayOfLastYear DATETIME = CONVERT(DATE, DATEADD(ms, -2, DATEADD(YEAR, 0, DATEADD(YEAR, DATEDIFF(YEAR, 0, GETDATE()), 0))))
, @FirstDayOfNextYear DATETIME = CONVERT(DATE, DATEADD(YEAR, DATEDIFF(YEAR, 0, GETDATE()) + 1, 0))
, @LastDayOfNextYear DATETIME = CONVERT(DATE, DATEADD(ms, -2, DATEADD(YEAR, 0, DATEADD(YEAR, DATEDIFF(YEAR, 0, GETDATE()) + 2, 0))))
SELECT
'a) FirstDayOfCurrentWeek.' AS [Title] ,
@FirstDayOfCurrentWeek AS [DATE (Server default)] ,
CONVERT(VARCHAR, @FirstDayOfCurrentWeek, 127) AS [ISO8601] ,
CONVERT(VARCHAR, @FirstDayOfCurrentWeek, 103) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [British&French] ,
CONVERT(VARCHAR, @FirstDayOfCurrentWeek, 104) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [German] ,
CONVERT(VARCHAR, @FirstDayOfCurrentWeek, 105) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [Italian] ,
CONVERT(VARCHAR, @FirstDayOfCurrentWeek, 111) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [Japan] ,
CONVERT(VARCHAR, @FirstDayOfCurrentWeek, 100) AS [U.S.] ,
CONVERT(VARCHAR, @FirstDayOfCurrentWeek, 120) AS [ODBC]
UNION
SELECT
'b) LastDayOfCurrentWeek.' AS [Title] ,
@LastDayOfCurrentWeek AS [DATE (Server default)] ,
CONVERT(VARCHAR, @LastDayOfCurrentWeek, 127) AS [ISO8601] ,
CONVERT(VARCHAR, @LastDayOfCurrentWeek, 103) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [British&French] ,
CONVERT(VARCHAR, @LastDayOfCurrentWeek, 104) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [German] ,
CONVERT(VARCHAR, @LastDayOfCurrentWeek, 105) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [Italian] ,
CONVERT(VARCHAR, @LastDayOfCurrentWeek, 111) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [Japan] ,
CONVERT(VARCHAR, @LastDayOfCurrentWeek, 100) AS [U.S.] ,
CONVERT(VARCHAR, @LastDayOfCurrentWeek, 120) AS [ODBC]
UNION
SELECT
'c) FirstDayOfLastWeek.' AS [Title] ,
@FirstDayOfLastWeek AS [DATE (Server default)] ,
CONVERT(VARCHAR, @FirstDayOfLastWeek, 127) AS [ISO8601] ,
CONVERT(VARCHAR, @FirstDayOfLastWeek, 103) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [British&French] ,
CONVERT(VARCHAR, @FirstDayOfLastWeek, 104) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [German] ,
CONVERT(VARCHAR, @FirstDayOfLastWeek, 105) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [Italian] ,
CONVERT(VARCHAR, @FirstDayOfLastWeek, 111) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [Japan] ,
CONVERT(VARCHAR, @FirstDayOfLastWeek, 100) AS [U.S.] ,
CONVERT(VARCHAR, @FirstDayOfLastWeek, 120) AS [ODBC]
UNION
SELECT
'd) LastDayOfLastWeek.' AS [Title] ,
@LastDayOfLastWeek AS [DATE (Server default)] ,
CONVERT(VARCHAR, @LastDayOfLastWeek, 127) AS [ISO8601] ,
CONVERT(VARCHAR, @LastDayOfLastWeek, 103) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [British&French] ,
CONVERT(VARCHAR, @LastDayOfLastWeek, 104) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [German] ,
CONVERT(VARCHAR, @LastDayOfLastWeek, 105) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [Italian] ,
CONVERT(VARCHAR, @LastDayOfLastWeek, 111) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [Japan] ,
CONVERT(VARCHAR, @LastDayOfLastWeek, 100) AS [U.S.] ,
CONVERT(VARCHAR, @LastDayOfLastWeek, 120) AS [ODBC]
UNION
SELECT
'e) FirstDayOfNextWeek.' AS [Title] ,
@FirstDayOfNextWeek AS [DATE (Server default)] ,
CONVERT(VARCHAR, @FirstDayOfNextWeek, 127) AS [ISO8601] ,
CONVERT(VARCHAR, @FirstDayOfNextWeek, 103) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [British&French] ,
CONVERT(VARCHAR, @FirstDayOfNextWeek, 104) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [German] ,
CONVERT(VARCHAR, @FirstDayOfNextWeek, 105) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [Italian] ,
CONVERT(VARCHAR, @FirstDayOfNextWeek, 111) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [Japan] ,
CONVERT(VARCHAR, @FirstDayOfNextWeek, 100) AS [U.S.] ,
CONVERT(VARCHAR, @FirstDayOfNextWeek, 120) AS [ODBC]
UNION
SELECT
'f) LastDayOfNextWeek.' AS [Title] ,
@LastDayOfNextWeek AS [DATE (Server default)] ,
CONVERT(VARCHAR, @LastDayOfNextWeek, 127) AS [ISO8601] ,
CONVERT(VARCHAR, @LastDayOfNextWeek, 103) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [British&French] ,
CONVERT(VARCHAR, @LastDayOfNextWeek, 104) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [German] ,
CONVERT(VARCHAR, @LastDayOfNextWeek, 105) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [Italian] ,
CONVERT(VARCHAR, @LastDayOfNextWeek, 111) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [Japan] ,
CONVERT(VARCHAR, @LastDayOfNextWeek, 100) AS [U.S.] ,
CONVERT(VARCHAR, @LastDayOfNextWeek, 120) AS [ODBC]
UNION
SELECT
'g) FirstDayOfCurrentMonth.' AS [Title] ,
@FirstDayOfCurrentMonth AS [DATE (Server default)] ,
CONVERT(VARCHAR, @FirstDayOfCurrentMonth, 127) AS [ISO8601] ,
CONVERT(VARCHAR, @FirstDayOfCurrentMonth, 103) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [British&French] ,
CONVERT(VARCHAR, @FirstDayOfCurrentMonth, 104) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [German] ,
CONVERT(VARCHAR, @FirstDayOfCurrentMonth, 105) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [Italian] ,
CONVERT(VARCHAR, @FirstDayOfCurrentMonth, 111) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [Japan] ,
CONVERT(VARCHAR, @FirstDayOfCurrentMonth, 100) AS [U.S.] ,
CONVERT(VARCHAR, @FirstDayOfCurrentMonth, 120) AS [ODBC]
UNION
SELECT
'h) LastDayOfCurrentMonth.' AS [Title] ,
@LastDayOfCurrentMonth AS [DATE (Server default)] ,
CONVERT(VARCHAR, @LastDayOfCurrentMonth, 127) AS [ISO8601] ,
CONVERT(VARCHAR, @LastDayOfCurrentMonth, 103) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [British&French] ,
CONVERT(VARCHAR, @LastDayOfCurrentMonth, 104) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [German] ,
CONVERT(VARCHAR, @LastDayOfCurrentMonth, 105) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [Italian] ,
CONVERT(VARCHAR, @LastDayOfCurrentMonth, 111) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [Japan] ,
CONVERT(VARCHAR, @LastDayOfCurrentMonth, 100) AS [U.S.] ,
CONVERT(VARCHAR, @LastDayOfCurrentMonth, 120) AS [ODBC]
UNION
SELECT
'i) FirstDayOfLastMonth.' AS [Title] ,
@FirstDayOfLastMonth AS [DATE (Server default)] ,
CONVERT(VARCHAR, @FirstDayOfLastMonth, 127) AS [ISO8601] ,
CONVERT(VARCHAR, @FirstDayOfLastMonth, 103) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [British&French] ,
CONVERT(VARCHAR, @FirstDayOfLastMonth, 104) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [German] ,
CONVERT(VARCHAR, @FirstDayOfLastMonth, 105) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [Italian] ,
CONVERT(VARCHAR, @FirstDayOfLastMonth, 111) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [Japan] ,
CONVERT(VARCHAR, @FirstDayOfLastMonth, 100) AS [U.S.] ,
CONVERT(VARCHAR, @FirstDayOfLastMonth, 120) AS [ODBC]
UNION
SELECT
'j) LastDayOfLastMonth.' AS [Title] ,
@LastDayOfLastMonth AS [DATE (Server default)] ,
CONVERT(VARCHAR, @LastDayOfLastMonth, 127) AS [ISO8601] ,
CONVERT(VARCHAR, @LastDayOfLastMonth, 103) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [British&French] ,
CONVERT(VARCHAR, @LastDayOfLastMonth, 104) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [German] ,
CONVERT(VARCHAR, @LastDayOfLastMonth, 105) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [Italian] ,
CONVERT(VARCHAR, @LastDayOfLastMonth, 111) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [Japan] ,
CONVERT(VARCHAR, @LastDayOfLastMonth, 100) AS [U.S.] ,
CONVERT(VARCHAR, @LastDayOfLastMonth, 120) AS [ODBC]
UNION
SELECT
'k) FirstDayOfNextMonth.' AS [Title] ,
@FirstDayOfNextMonth AS [DATE (Server default)] ,
CONVERT(VARCHAR, @FirstDayOfNextMonth, 127) AS [ISO8601] ,
CONVERT(VARCHAR, @FirstDayOfNextMonth, 103) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [British&French] ,
CONVERT(VARCHAR, @FirstDayOfNextMonth, 104) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [German] ,
CONVERT(VARCHAR, @FirstDayOfNextMonth, 105) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [Italian] ,
CONVERT(VARCHAR, @FirstDayOfNextMonth, 111) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [Japan] ,
CONVERT(VARCHAR, @FirstDayOfNextMonth, 100) AS [U.S.] ,
CONVERT(VARCHAR, @FirstDayOfNextMonth, 120) AS [ODBC]
UNION
SELECT
'l) LastDayOfNextMonth.' AS [Title] ,
@LastDayOfNextMonth AS [DATE (Server default)] ,
CONVERT(VARCHAR, @LastDayOfNextMonth, 127) AS [ISO8601] ,
CONVERT(VARCHAR, @LastDayOfNextMonth, 103) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [British&French] ,
CONVERT(VARCHAR, @LastDayOfNextMonth, 104) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [German] ,
CONVERT(VARCHAR, @LastDayOfNextMonth, 105) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [Italian] ,
CONVERT(VARCHAR, @LastDayOfNextMonth, 111) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [Japan] ,
CONVERT(VARCHAR, @LastDayOfNextMonth, 100) AS [U.S.] ,
CONVERT(VARCHAR, @LastDayOfNextMonth, 120) AS [ODBC]
UNION
SELECT
'm) FirstDayOfCurrentYear.' AS [Title] ,
@FirstDayOfCurrentYear AS [DATE (Server default)] ,
CONVERT(VARCHAR, @FirstDayOfCurrentYear, 127) AS [ISO8601] ,
CONVERT(VARCHAR, @FirstDayOfCurrentYear, 103) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [British&French] ,
CONVERT(VARCHAR, @FirstDayOfCurrentYear, 104) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [German] ,
CONVERT(VARCHAR, @FirstDayOfCurrentYear, 105) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [Italian] ,
CONVERT(VARCHAR, @FirstDayOfCurrentYear, 111) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [Japan] ,
CONVERT(VARCHAR, @FirstDayOfCurrentYear, 100) AS [U.S.] ,
CONVERT(VARCHAR, @FirstDayOfCurrentYear, 120) AS [ODBC]
UNION
SELECT
'n) LastDayOfCurrentYear.' AS [Title] ,
@LastDayOfCurrentYear AS [DATE (Server default)] ,
CONVERT(VARCHAR, @LastDayOfCurrentYear, 127) AS [ISO8601] ,
CONVERT(VARCHAR, @LastDayOfCurrentYear, 103) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [British&French] ,
CONVERT(VARCHAR, @LastDayOfCurrentYear, 104) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [German] ,
CONVERT(VARCHAR, @LastDayOfCurrentYear, 105) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [Italian] ,
CONVERT(VARCHAR, @LastDayOfCurrentYear, 111) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [Japan] ,
CONVERT(VARCHAR, @LastDayOfCurrentYear, 100) AS [U.S.] ,
CONVERT(VARCHAR, @LastDayOfCurrentYear, 120) AS [ODBC]
UNION
SELECT
'o) FirstDayOfLastYear.' AS [Title] ,
@FirstDayOfLastYear AS [DATE (Server default)] ,
CONVERT(VARCHAR, @FirstDayOfLastYear, 127) AS [ISO8601] ,
CONVERT(VARCHAR, @FirstDayOfLastYear, 103) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [British&French] ,
CONVERT(VARCHAR, @FirstDayOfLastYear, 104) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [German] ,
CONVERT(VARCHAR, @FirstDayOfLastYear, 105) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [Italian] ,
CONVERT(VARCHAR, @FirstDayOfLastYear, 111) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [Japan] ,
CONVERT(VARCHAR, @FirstDayOfLastYear, 100) AS [U.S.] ,
CONVERT(VARCHAR, @FirstDayOfLastYear, 120) AS [ODBC]
UNION
SELECT
'p) LastDayOfLastYear.' AS [Title] ,
@LastDayOfLastYear AS [DATE (Server default)] ,
CONVERT(VARCHAR, @LastDayOfLastYear, 127) AS [ISO8601] ,
CONVERT(VARCHAR, @LastDayOfLastYear, 103) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [British&French] ,
CONVERT(VARCHAR, @LastDayOfLastYear, 104) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [German] ,
CONVERT(VARCHAR, @LastDayOfLastYear, 105) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [Italian] ,
CONVERT(VARCHAR, @LastDayOfLastYear, 111) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [Japan] ,
CONVERT(VARCHAR, @LastDayOfLastYear, 100) AS [U.S.] ,
CONVERT(VARCHAR, @LastDayOfLastYear, 120) AS [ODBC]
UNION
SELECT
'q) FirstDayOfNextYear.' AS [Title] ,
@FirstDayOfNextYear AS [DATE (Server default)] ,
CONVERT(VARCHAR, @FirstDayOfNextYear, 127) AS [ISO8601] ,
CONVERT(VARCHAR, @FirstDayOfNextYear, 103) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [British&French] ,
CONVERT(VARCHAR, @FirstDayOfNextYear, 104) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [German] ,
CONVERT(VARCHAR, @FirstDayOfNextYear, 105) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [Italian] ,
CONVERT(VARCHAR, @FirstDayOfNextYear, 111) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [Japan] ,
CONVERT(VARCHAR, @FirstDayOfNextYear, 100) AS [U.S.] ,
CONVERT(VARCHAR, @FirstDayOfNextYear, 120) AS [ODBC]
UNION
SELECT
'r) LastDayOfNextYear.' AS [Title] ,
@LastDayOfNextYear AS [DATE (Server default)] ,
CONVERT(VARCHAR, @LastDayOfNextYear, 127) AS [ISO8601] ,
CONVERT(VARCHAR, @LastDayOfNextYear, 103) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [British&French] ,
CONVERT(VARCHAR, @LastDayOfNextYear, 104) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [German] ,
CONVERT(VARCHAR, @LastDayOfNextYear, 105) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [Italian] ,
CONVERT(VARCHAR, @LastDayOfNextYear, 111) + ' ' + CONVERT(CHAR(5), @FirstDayOfCurrentWeek, 108) AS [Japan] ,
CONVERT(VARCHAR, @LastDayOfNextYear, 100) AS [U.S.] ,
CONVERT(VARCHAR, @LastDayOfNextYear, 120) AS [ODBC];
Run the above code to produce the following output:

If your country is missing, then it is because I don't know the code for it. It would be most helpful and appreciated if you could please edit this answer and add a new column for your country.
Thanks in advance.
Note: Bear in mind that today's date for me is 12th September, 2016.
References
For further reading on the ISO8601 international date standard, follow this link:
For further reading on the ODBC international date standard, follow this link:
To view the list of date formats I worked from, follow this link:
For further reading on the DATETIME data type, follow this link: