I am writing a function in T-SQL returning the last day of the month regardless of the date input.
Here is my code:
Alter Function dbo.FN_Get_Last_Day_in_Month2
(#FN_InputDt Datetime)
Returns smalldatetime
as
Begin
Declare #Result smalldatetime
Set #Result =
case when #FN_InputDt <> 01-01-1900 then
DATEADD(m, DATEDIFF(M, 0,#FN_InputDt)+1, -1)
Else 0 End
Return #Result
End
The code is not working correctly, here is a test that shows the bad behavior:
SELECT dbo.fn_get_last_day_in_month (07-05-2010)
Here is the (incorrect) result:
2010-07-31 00:00:00
What is 07-05-2010...May 7th or July 5th? You need to use a safe date format, take a look at Setting a standard DateFormat for SQL Server
example from How to find the first and last days in years, months etc
DECLARE #d DATETIME
SET #d = '20100705' -- notice ISO format
SELECT
DATEADD(yy, DATEDIFF(yy, 0, #d), 0) AS FirstDayOfYear,
DATEADD(yy, DATEDIFF(yy, 0, #d)+1, -1) AS LastDayOfYear,
DATEADD(qq, DATEDIFF(qq, 0, #d), 0) AS FirstDayOfQuarter,
DATEADD(qq, DATEDIFF(qq, 0, #d)+1, -1) AS LastDayOfQuarter,
DATEADD(mm, DATEDIFF(mm, 0, #d), 0) AS FirstDayOfMonth,
DATEADD(mm, DATEDIFF(mm, 0, #d)+1, -1) AS LastDayOfMonth,
#d - DATEDIFF(dd, ##DATEFIRST - 1, #d) % 7 AS FirstDayOfWeek,
#d - DATEDIFF(dd, ##DATEFIRST - 1, #d) % 7 + 6 AS LastDayOfWeek
for just the day use day or datepart
select DAY(getdate()),
DATEPART(dd,GETDATE())
Cast the return value to a SQL datetime type, and then call the "DAY" function to get the day in as an integer. See the function reference here:
http://msdn.microsoft.com/en-us/library/ms176052.aspx
Not sure which database you're using, but this should be a standard function across all databases.
I'd return a DATETIME, I've had trouble with SMALLDATETIME in the past.
DECLARE #Result DATETIME
SET #Result = DATEADD(m , 1, #FN_Input);
RETURN CAST(FLOOR(CAST(DATEADD(d, DATEPART(d, #Result) * -1, #Result) AS FLOAT)) AS DATETIME)
Also, I think you may be a victim of SQL's complete disregard of date formatting. Always, always, always, when typing a string into test a SQL function use the following format;
'05 Jul 2010'
Your function probably works but it interpreted your date as 5th July - not 7th May.
DECLARE #date DATETIME = '20130624';
SELECT Day(EOMONTH ( #date )) AS LastDay;
GO
Related
I am trying to write this Excel formula into T-SQL (to write a function).
Expected output is 0.71944444, but currently my output (using T-SQL) is 24.0000.
I am not sure why we have to add a day to same date and subtract the same date.
Bottom is a screenshot from Excel:
This is what I have so far in T-SQL:
CREATE FUNCTION [dbo].[fn_0921] (
#Punch_Start nvarchar(max)
)
RETURNS decimal(36, 8) AS
BEGIN
DECLARE #return_value nvarchar(max);
SET #return_value =
DATEDIFF(
MINUTE, CAST(#Punch_Start AS datetime2),
(
dateadd(
day, 1, CAST(#Punch_Start AS datetime2)
)
)
)
/ (60.0)
RETURN #return_value
END;
Thanks for help.
The Excel formula is returning the difference between the datetime in cell K4 & the start of the next day (i.e. 7/26/2021 00:00) as a fraction of a whole day. The following is the equivalent in T-SQL:
DECLARE #Punch_Start datetime2 = '7/25/2021 06:44';
SELECT DATEDIFF(
MINUTE,
#Punch_Start,
CAST(
CAST(
DATEADD(DAY, 1, #Punch_Start)
AS date) -- Add 1 day to #Punch_Start & cast as date to remove the time component - this is the start of the next day
AS datetime2) -- Cast back to datetime2 to get the difference in minutes
) / 1440.; -- Divide the difference in minutes by the number of minutes in a day (60 minutes per hour, 24 hours per day) to get the difference as a fraction of a day
This can probably help you:
DECLARE #date DATETIME2 = '2021-07-25 06:44'
DECLARE #seconds INT = DATEDIFF(second, CAST(#date AS date), #date)
DECLARE #secondsFromEnd FLOAT = 86400 - #seconds
SELECT #secondsFromEnd / 86400
I need a calculated month value within DATEFROMPARTS function. The month has to be seven month prior to CURRENT_TIMESTAMP month.
This is what I tried:
DATEFROMPARTS(Year(CURRENT_TIMESTAMP), Month(CURRENT_TIMESTAMP)-7, 1) as SevenMoAgo;
I will eventually use this in the following expression where '12-01-2018' is:
where RECORDED_SERVICE_STARTTIME > ='12-01-2018'
I later used
declare #CurMo AS INT;
declare #MonPri7 AS INT;
set #CurMo = Month(CURRENT_TIMESTAMP);
set #MonPri7 = (#CurMo -7);
Datefromparts(Year(CURRENT_TIMESTAMP), #MonPri7, 1) as SevenMoAgo;
This also did not work.
I get the following error message:
"Cannot construct data type date, some of the arguments have values which are not valid."
For the second code I get:
Msg 102, Level 15, State 1, Line 8
Incorrect syntax near 'Datefromparts'.
Try this...
SELECT DATEADD(MONTH, DATEDIFF(MONTH, 0, CURRENT_TIMESTAMP) - 7, 0)
Let me explain. First off, we need to understand that SQL Server interprets 0 as 1900-01-01 as shown by the following DATEPART functions.
SELECT DATEPART(YEAR, 0) AS Year
, DATEPART(MONTH, 0) AS Month
, DATEPART(DAY, 0) AS Day;
Which returns...
Year Month Day
----------- ----------- -----------
1900 1 1
Therefore, my SQL could be rewritten as...
SELECT DATEADD(MONTH, DATEDIFF(MONTH, '1900-01-01', CURRENT_TIMESTAMP) - 7, '1900-01-01')
Now perhaps it is a little easier to see what is going on here. The DATEDIFF function returns the number number of months between 1900-01-01 and today (CURRENT_TIMESTAMP) which is 1434.
SELECT DATEADD(MONTH, 1434 - 7, '1900-01-01')
Then we subtract 7 from 1434 which is 1427 and add that many months back to 1900-01-01.
SELECT DATEADD(MONTH, 1427, '1900-01-01')
Which yields 2018-12-01.
The reason is #MonPri7 is equal to ZERO when you say (#CurMo -7)
There are many different ways to calculate it, but if you want to fix your logic, you should use this:
declare #CurMo AS INT;
declare #MonPri7 AS INT;
set #CurMo = Month(CURRENT_TIMESTAMP);
set #MonPri7 = (#CurMo -7);
declare #Y int = Year(CURRENT_TIMESTAMP) -- <-- This is new variable
-- if 7 months ago is ZERO then you should go back to prev year December
if #MonPri7 = 0
begin
set #MonPri7 = 12
set #Y = #Y - 1
end
Edit:
declare #SevenMonthsAgo datetime;
select #SevenMonthsAgo = Datefromparts(#Y, #MonPri7, 1);
SELECT yourfields
FROM yourtable
where RECORDED_SERVICE_STARTTIME > = '01-01-2019' and
RECORDED_SERVICE_STARTTIME > = #SevenMonthsAgo
I need to show N records with each record being 1 weeks worth of summarized data. One of the inputs will be a date range.
Since each week should start with monday, I want to get a list of all the monday dates in the date range. Any suggestions to get that?
Note: This has to run on SQL 2005
declare #dt datetime
SET #dt = '2010-01-01'
declare #dtEnd datetime
SET #dtEnd = '2010-12-04'
DECLARE #day AS NVARCHAR(30)
WHILE (#dt < #dtEnd) BEGIN
-- insert into table(datefield)
-- values(#dt)
SET #day = UPPER(DATENAME(weekday,#dt))
IF #day = 'MONDAY'
--PRINT 'date is: ' + CAST(#dt AS VARCHAR(30))
BEGIN
PRINT 'date is: ' + CAST(#dt AS VARCHAR(30)) + ' ' + #day
END
SET #dt = DATEADD(day, 1, #dt)
END
The code you show seems to work, but it can be made more efficient. The code I show below will calculate the first Monday on or after the start date. Then it is used in the same loop but we simply add 7 days each time through the loop.
declare #dt datetime,
#dtEnd datetime
SET #dt = '2010-01-01'
SET #dtEnd = '2010-12-04'
Set #dt = DateAdd(Day, 7 - DateDiff(Day, 0, #dt) % 7, #dt)
WHILE (#dt < #dtEnd) BEGIN
PRINT 'date is: ' + CAST(#dt AS VARCHAR(30)) + ' ' + DateName(Weekday, #dt)
SET #dt = DATEADD(day, 7, #dt)
END
One thing I notice about your code is that you are using DateName, which works ok for displaying the weekday name, but not so good for making decisions (like you are doing). The problem with DateName is that it uses the language setting of the currently logged in user.
The following code shows this behavior.
set language 'spanish'
Select DateName(Weekday, GetDate())
set language 'us_english'
Select DateName(Weekday, GetDate())
Basically, if the language of a user was set to spanish, your code would fail but mine would not. Mine works because it uses the fact that January 1, 1900 was a Monday. It calculates the number of days and takes a mod of that and uses that mod to add the correct number of days. Since January 1, 1900 will always be a Monday, and we are not using the DateName function, this code will work without regard to the language setting.
SELECT * from table t
WHERE t.date between 'startDate' and 'endDate'
AND (SELECT DATEPART(dw,t.StudyDate))=2
I would like to contribute my codes related to the date conversion between local time and UTC time for both current and historical dates, including day light savings time consideration. I reviewed some recent postings but could not find the solution I am looking for so I summarize the solutions I found to develop my own solution. I am running my codes in SQL Server 2008R2. Test cases are provided as comments before each function. Feel free to check out the Credits section for related postings, try out my codes, and let me know if I miss anything. Thanks.
-- Test 1: select dbo.fn_isDayLightSavings(CAST('2014-01-01' AS DATE)), expect 0
-- Test 2: select dbo.fn_isDayLightSavings(CAST('2014-04-14' AS DATE)), expect 1
IF OBJECT_ID(N'fn_isDayLightSavings') IS NOT NULL AND OBJECTPROPERTY(OBJECT_ID(N'fn_isDayLightSavings'),'IsScalarFunction') = 1
DROP FUNCTION fn_isDayLightSavings;
GO
CREATE FUNCTION fn_isDayLightSavings (#dt AS DATETIME)
RETURNS TINYINT
AS
BEGIN
DECLARE #rtn TINYINT, #year INT, #dtsStartMonth DATETIME, #dtsEndMonth DATETIME, #dstStart DATETIME, #dstEnd DATETIME;
SET #year = DATEPART(YEAR, #dt);
-- In year 2007, US day light savings period changes from Apr-Oct to Mar-Nov.
if #year < 2007
BEGIN
-- Last Sunday of April at 2 AM
SET #dtsStartMonth = DATEADD(MONTH, 4, DATEADD(YEAR, #year - 1900, 0));
SET #dstStart = DATEADD(HOUR, 2, DATEADD(day, -(DATEPART(dw, #dtsStartMonth) - 1), #dtsStartMonth));
-- Last Sunday of October at 2 AM
SET #dtsEndMonth = DATEADD(MONTH, 10, DATEADD(YEAR, #year - 1900, 0));
SET #dstEnd = DATEADD(HOUR, 2, DATEADD(day, -(DATEPART(dw, #dtsEndMonth) - 1), #dtsEndMonth));
END
else
BEGIN
-- 2nd Sunday of March at 2 AM
SET #dtsStartMonth = DATEADD(MONTH, 2, DATEADD(YEAR, #year - 1900, 0));
SET #dstStart = DATEADD(HOUR, 2, DATEADD(day, ((15 - DATEPART(dw, #dtsStartMonth)) % 7) + 7, #dtsStartMonth));
-- 1st Sunday of November at 2 AM
SET #dtsEndMonth = DATEADD(MONTH, 10, DATEADD(YEAR, #year - 1900, 0));
SET #dstEnd = DATEADD(HOUR, 2, DATEADD(day, ((8 - DATEPART(dw, #dtsEndMonth)) % 7) + 7, #dtsEndMonth));
END
if #dt BETWEEN #dstStart AND #dstEnd SET #rtn=1 ELSE SET #rtn=0;
RETURN #rtn;
END
GO
-- Test 1: select dbo.fn_DateTime2UTC(CAST('2014-01-01 01:00:00' AS DATETIME), 0), expect '2014-01-01 07:00:00.000'
-- Test 2: select dbo.fn_DateTime2UTC(CAST('2014-01-01 01:00:00' AS DATETIME), 1), expect '2013-01-01 07:00:00.000'
-- Test 3: select dbo.fn_DateTime2UTC(CAST('2014-05-01 01:00:00' AS DATETIME), 0), expect '2014-05-01 06:00:00.000'
-- Test 4: select dbo.fn_DateTime2UTC(CAST('2014-05-01 01:00:00' AS DATETIME), 1), expect '2014-05-01 07:00:00.000'
IF OBJECT_ID(N'fn_DateTime2UTC') IS NOT NULL AND OBJECTPROPERTY(OBJECT_ID(N'fn_DateTime2UTC'),'IsScalarFunction') = 1
DROP FUNCTION fn_DateTime2UTC;
GO
CREATE FUNCTION fn_DateTime2UTC (#dt AS DATETIME, #ignoreDST AS TINYINT = 0)
-- do CAST(? AS DATETIMEOFFSET), if need datetimeoffset type
RETURNS DATETIME
AS
BEGIN
DECLARE #tzOffset INT, #utcDt DATETIME;
-- Get current time zone offset in minutes
SET #tzOffset = DATEPART(TZoffset, SYSDATETIMEOFFSET()) +
(CASE WHEN dbo.fn_isDayLightSavings(#dt)=1 THEN 60 ELSE 0 END);
if dbo.fn_isDayLightSavings(#dt)=0
set #utcDt = DATEADD(MINUTE, -#tzOffset, #dt);
else if #ignoreDST=0
set #utcDt = DATEADD(MINUTE, -#tzOffset, #dt);
else
set #utcDt = DATEADD(MINUTE, -#tzOffset+60, #dt);
return #utcDt;
END
GO
-- Test 1: select dbo.fn_UTC2DateTime(CAST('2014-01-01 07:00:00.000' AS DATETIME), 0), expect '2014-01-01 01:00:00'
-- Test 2: select dbo.fn_UTC2DateTime(CAST('2013-01-01 07:00:00.000' AS DATETIME), 1), expect '2014-01-01 01:00:00'
-- Test 3: select dbo.fn_UTC2DateTime(CAST('2014-05-01 06:00:00.000' AS DATETIME), 0), expect '2014-05-01 01:00:00'
-- Test 4: select dbo.fn_UTC2DateTime(CAST('2014-05-01 07:00:00.000' AS DATETIME), 1), expect '2014-05-01 01:00:00'
IF OBJECT_ID(N'fn_UTC2DateTime') IS NOT NULL AND OBJECTPROPERTY(OBJECT_ID(N'fn_UTC2DateTime'),'IsScalarFunction') = 1
DROP FUNCTION fn_UTC2DateTime;
GO
CREATE FUNCTION fn_UTC2DateTime (#utcDt AS DATETIME, #ignoreDST AS TINYINT = 0)
RETURNS DATETIME
AS
BEGIN
DECLARE #tzOffset INT, #dt DATETIME;
-- Get current time zone offset in minutes
SET #tzOffset = DATEPART(TZoffset, SYSDATETIMEOFFSET()) +
(CASE WHEN dbo.fn_isDayLightSavings(#utcDt)=1 THEN 60 ELSE 0 END);
if dbo.fn_isDayLightSavings(#utcDt)=0
set #dt = DATEADD(MINUTE, #tzOffset, #utcDt);
else if #ignoreDST=0
set #dt = DATEADD(MINUTE, #tzOffset, #utcDt);
else
set #dt = DATEADD(MINUTE, #tzOffset-60, #utcDt);
return #dt;
END
GO
-- Test 1: select dbo.fn_UTC2DateTimeOffset(CAST('2014-01-01 07:00:00.000' AS DATETIME), 0), expect '2014-01-01 01:00:00.0000000 -06:00'
-- Test 2: select dbo.fn_UTC2DateTimeOffset(CAST('2013-01-01 07:00:00.000' AS DATETIME), 1), expect '2014-01-01 01:00:00.0000000 -06:00'
-- Test 3: select dbo.fn_UTC2DateTimeOffset(CAST('2014-05-01 06:00:00.000' AS DATETIME), 0), expect '2014-05-01 01:00:00.0000000 -05:00'
-- Test 4: select dbo.fn_UTC2DateTimeOffset(CAST('2014-05-01 07:00:00.000' AS DATETIME), 1), expect '2014-05-01 00:00:00.0000000 -06:00'
IF OBJECT_ID(N'fn_UTC2DateTimeOffset') IS NOT NULL AND OBJECTPROPERTY(OBJECT_ID(N'fn_UTC2DateTimeOffset'),'IsScalarFunction') = 1
DROP FUNCTION fn_UTC2DateTimeOffset;
GO
CREATE FUNCTION fn_UTC2DateTimeOffset (#utcDt AS DATETIME, #ignoreDST TINYINT = 0)
RETURNS DATETIMEOFFSET
AS
BEGIN
DECLARE #tzOffset INT, #dt DATETIMEOFFSET;
-- Get current time zone offset in minutes
SET #tzOffset = DATEPART(TZoffset, SYSDATETIMEOFFSET()) +
(CASE WHEN dbo.fn_isDayLightSavings(#utcDt)=1 THEN 60 ELSE 0 END);
if dbo.fn_isDayLightSavings(#utcDt)=0
set #dt = SWITCHOFFSET(CAST(#utcDt AS DATETIMEOFFSET), #tzOffset);
else if #ignoreDST=0
set #dt = SWITCHOFFSET(CAST(#utcDt AS DATETIMEOFFSET), #tzOffset);
else
set #dt = SWITCHOFFSET(CAST(#utcDt AS DATETIMEOFFSET), #tzOffset-60);
return #dt;
END
GO
-- Credits:
-- Determination of day light savings start and end time, Jamie F., 11/1/2013
-- (http://stackoverflow.com/questions/19732896/how-to-create-daylight-savings-time-start-and-end-function-in-sql-server)
-- Day light savings time calendar, USNO
-- (http://aa.usno.navy.mil/faq/docs/daylight_time.php)
-- Time zone offset, Microsoft
-- (http://msdn.microsoft.com/en-us/library/ms174420.aspx)
-- Local system date time with time zone, Robert Cantor, 12/7/2013
-- (http://stackoverflow.com/questions/1205142/tsql-how-to-convert-local-time-to-utc-sqlserver2008)
-- Convert date with time zone and day light savings, Eric Z Beard, 8/24/2008
-- (http://stackoverflow.com/questions/24797/effectively-converting-dates-between-utc-and-local-ie-pst-time-in-sql-2005#25073)
Kudos to you for assembling that knowledge into one place. Assuming it is accurate, it's easy to pick up and use immediately.
However, the trouble is that without an extensive set of unit tests you can't be sure of accuracy.
Might I suggest the best option for date/time conversions would be to use an existing highly tested open source library such as http://nodatime.org/. Date/time conversions have so many intracacies and details that could not possibly be contained in a few dozen lines of SQL code.
nodatime is a .NET library that should easily be accessible via the SQL Server CLR user-defined functions feature.
How do you calculate the number of weeks between two dates?
for example as follows
Declare #StartDate as DateTime = "01 Jan 2009";
Declare #EndDate as DateTime = "01 June 2009";
#StartDate and #EndDate
Use the Datediff function. datediff(ww,#startdate,#enddate)
the ww tells the function what units you require the difference to be counted in.
http://msdn.microsoft.com/en-us/library/ms189794.aspx
You may use the following function to retrives week's between two dates:
CREATE FUNCTION [dbo].[fGetWeeksList]
(
#StartDate DATETIME
,#EndDate DATETIME
)
RETURNS
TABLE
AS
RETURN
(
SELECT DATEADD(DAY,-(DATEPART(DW,DATEADD(WEEK, x.number, #StartDate))-2),DATEADD(WEEK, x.number, #StartDate)) as [StartDate]
,DATEADD(DAY,-(DATEPART(DW,DATEADD(WEEK, x.number + 1, #StartDate))-1) ,DATEADD(WEEK, x.number + 1, #StartDate)) AS [EndDate]
FROM master.dbo.spt_values x
WHERE x.type = 'P' AND x.number <= DATEDIFF(WEEK, #StartDate, DATEADD(WEEK,0,CAST(#EndDate AS DATE)))