how do I get the EXACT number of months between two dates? - sql

DATEDIFF(MONTH, '1/1/2014', '12/31/2014') + 1
This will give me 12.
What if I do this:
DATEDIFF(MONTH, '1/1/2014', '12/30/2014') + 1
It should give me 11 point something. How do I go about getting the exact number of months between these two dates? This needs to work for any combination of dates (any month of the year for any year).


You could do the calculation yourself in the following way:
DECLARE #startdate date = '1/1/2014'
DECLARE #enddate date = '12/30/2014'
DECLARE #startday int = DATEPART(DAY, #startdate)
DECLARE #endday int = DATEPART(DAY, #enddate)
DECLARE #startdateBase date = DATEADD(DAY, 1 - #startday, #startdate)
DECLARE #enddateBase date = DATEADD(DAY, 1 - #endday, #enddate)
DECLARE #deciMonthDiff float = CAST(DATEDIFF(MONTH, #startdate, #enddate) AS float) -
(#startday - 1.0) / DATEDIFF(DAY, #startdateBase, DATEADD(MONTH, 1, #startdateBase)) +
(#endday - 1.0) / DATEDIFF(DAY, #enddateBase, DATEADD(MONTH, 1, #enddateBase))
SELECT #deciMonthDiff
This calculates the #deciMonthDiff to be 11.935483870967.
Of course you can "inline" this as much as you want in order to avoid all the middle declarations.
The idea is to calculate the total month diff, then subtract the relative part of the first & last month depending on the actual day.


DATEDIFF with the MONTH option only returns an integer value. Using days or years would give you a rough "guesstimate" but still not exactly right (different number of days in a month/year so you can't just divide the days difference by 30).
If you want exact you would need to write your own function to walk through the months from start until end and account for how many days are in each month and get a percentage/factor of that month covered.


DECLARE #startdate date = '1/1/2014'
DECLARE #enddate date = '12/30/2014'
select case when DATEPART(DAY, #startdate) <= DATEPART(DAY, #enddate)
then datediff(month, #startdate, #enddate)
else datediff(month, #startdate, #enddate) -1
end
from Chris The Jedi of T-SQL

Related

Datetime2 Overflow Issue [duplicate]

I have a table listing people along with their date of birth (currently a nvarchar(25))
How can I convert that to a date, and then calculate their age in years?
My data looks as follows
ID Name DOB
1 John 1992-01-09 00:00:00
2 Sally 1959-05-20 00:00:00
I would like to see:
ID Name AGE DOB
1 John 17 1992-01-09 00:00:00
2 Sally 50 1959-05-20 00:00:00

There are issues with leap year/days and the following method, see the update below:
try this:
DECLARE #dob datetime
SET #dob='1992-01-09 00:00:00'
SELECT DATEDIFF(hour,#dob,GETDATE())/8766.0 AS AgeYearsDecimal
,CONVERT(int,ROUND(DATEDIFF(hour,#dob,GETDATE())/8766.0,0)) AS AgeYearsIntRound
,DATEDIFF(hour,#dob,GETDATE())/8766 AS AgeYearsIntTrunc
OUTPUT:
AgeYearsDecimal AgeYearsIntRound AgeYearsIntTrunc
--------------------------------------- ---------------- ----------------
17.767054 18 17
(1 row(s) affected)
UPDATE here are some more accurate methods:
BEST METHOD FOR YEARS IN INT
DECLARE #Now datetime, #Dob datetime
SELECT #Now='1990-05-05', #Dob='1980-05-05' --results in 10
--SELECT #Now='1990-05-04', #Dob='1980-05-05' --results in 9
--SELECT #Now='1989-05-06', #Dob='1980-05-05' --results in 9
--SELECT #Now='1990-05-06', #Dob='1980-05-05' --results in 10
--SELECT #Now='1990-12-06', #Dob='1980-05-05' --results in 10
--SELECT #Now='1991-05-04', #Dob='1980-05-05' --results in 10
SELECT
(CONVERT(int,CONVERT(char(8),#Now,112))-CONVERT(char(8),#Dob,112))/10000 AS AgeIntYears
you can change the above 10000 to 10000.0 and get decimals, but it will not be as accurate as the method below.
BEST METHOD FOR YEARS IN DECIMAL
DECLARE #Now datetime, #Dob datetime
SELECT #Now='1990-05-05', #Dob='1980-05-05' --results in 10.000000000000
--SELECT #Now='1990-05-04', #Dob='1980-05-05' --results in 9.997260273973
--SELECT #Now='1989-05-06', #Dob='1980-05-05' --results in 9.002739726027
--SELECT #Now='1990-05-06', #Dob='1980-05-05' --results in 10.002739726027
--SELECT #Now='1990-12-06', #Dob='1980-05-05' --results in 10.589041095890
--SELECT #Now='1991-05-04', #Dob='1980-05-05' --results in 10.997260273973
SELECT 1.0* DateDiff(yy,#Dob,#Now)
+CASE
WHEN #Now >= DATEFROMPARTS(DATEPART(yyyy,#Now),DATEPART(m,#Dob),DATEPART(d,#Dob)) THEN --birthday has happened for the #now year, so add some portion onto the year difference
( 1.0 --force automatic conversions from int to decimal
* DATEDIFF(day,DATEFROMPARTS(DATEPART(yyyy,#Now),DATEPART(m,#Dob),DATEPART(d,#Dob)),#Now) --number of days difference between the #Now year birthday and the #Now day
/ DATEDIFF(day,DATEFROMPARTS(DATEPART(yyyy,#Now),1,1),DATEFROMPARTS(DATEPART(yyyy,#Now)+1,1,1)) --number of days in the #Now year
)
ELSE --birthday has not been reached for the last year, so remove some portion of the year difference
-1 --remove this fractional difference onto the age
* ( -1.0 --force automatic conversions from int to decimal
* DATEDIFF(day,DATEFROMPARTS(DATEPART(yyyy,#Now),DATEPART(m,#Dob),DATEPART(d,#Dob)),#Now) --number of days difference between the #Now year birthday and the #Now day
/ DATEDIFF(day,DATEFROMPARTS(DATEPART(yyyy,#Now),1,1),DATEFROMPARTS(DATEPART(yyyy,#Now)+1,1,1)) --number of days in the #Now year
)
END AS AgeYearsDecimal

Gotta throw this one out there. If you convert the date using the 112 style (yyyymmdd) to a number you can use a calculation like this...
(yyyyMMdd - yyyyMMdd) / 10000 = difference in full years
declare #as_of datetime, #bday datetime;
select #as_of = '2009/10/15', #bday = '1980/4/20'
select
Convert(Char(8),#as_of,112),
Convert(Char(8),#bday,112),
0 + Convert(Char(8),#as_of,112) - Convert(Char(8),#bday,112),
(0 + Convert(Char(8),#as_of,112) - Convert(Char(8),#bday,112)) / 10000
output
20091015 19800420 290595 29

I have used this query in our production code for nearly 10 years:
SELECT FLOOR((CAST (GetDate() AS INTEGER) - CAST(Date_of_birth AS INTEGER)) / 365.25) AS Age

You need to consider the way the datediff command rounds.
SELECT CASE WHEN dateadd(year, datediff (year, DOB, getdate()), DOB) > getdate()
THEN datediff(year, DOB, getdate()) - 1
ELSE datediff(year, DOB, getdate())
END as Age
FROM <table>
Which I adapted from here.
Note that it will consider 28th February as the birthday of a leapling for non-leap years e.g. a person born on 29 Feb 2020 will be considered 1 year old on 28 Feb 2021 instead of 01 Mar 2021.

So many of the above solutions are wrong DateDiff(yy,#Dob, #PassedDate) will not consider the month and day of both dates. Also taking the dart parts and comparing only works if they're properly ordered.
THE FOLLOWING CODE WORKS AND IS VERY SIMPLE:
create function [dbo].[AgeAtDate](
#DOB datetime,
#PassedDate datetime
)
returns int
with SCHEMABINDING
as
begin
declare #iMonthDayDob int
declare #iMonthDayPassedDate int
select #iMonthDayDob = CAST(datepart (mm,#DOB) * 100 + datepart (dd,#DOB) AS int)
select #iMonthDayPassedDate = CAST(datepart (mm,#PassedDate) * 100 + datepart (dd,#PassedDate) AS int)
return DateDiff(yy,#DOB, #PassedDate)
- CASE WHEN #iMonthDayDob <= #iMonthDayPassedDate
THEN 0
ELSE 1
END
End

EDIT: THIS ANSWER IS INCORRECT. I leave it in here as a warning to anyone tempted to use dayofyear, with a further edit at the end.
If, like me, you do not want to divide by fractional days or risk rounding/leap year errors, I applaud #Bacon Bits comment in a post above https://stackoverflow.com/a/1572257/489865 where he says:
If we're talking about human ages, you should calculate it the way
humans calculate age. It has nothing to do with how fast the earth
moves and everything to do with the calendar. Every time the same
month and day elapses as the date of birth, you increment age by 1.
This means the following is the most accurate because it mirrors what
humans mean when they say "age".
He then offers:
DATEDIFF(yy, #date, GETDATE()) -
CASE WHEN (MONTH(#date) > MONTH(GETDATE())) OR (MONTH(#date) = MONTH(GETDATE()) AND DAY(#date) > DAY(GETDATE()))
THEN 1 ELSE 0 END
There are several suggestions here involving comparing the month & day (and some get it wrong, failing to allow for the OR as correctly here!). But nobody has offered dayofyear, which seems so simple and much shorter. I offer:
DATEDIFF(year, #date, GETDATE()) -
CASE WHEN DATEPART(dayofyear, #date) > DATEPART(dayofyear, GETDATE()) THEN 1 ELSE 0 END
[Note: Nowhere in SQL BOL/MSDN is what DATEPART(dayofyear, ...) returns actually documented! I understand it to be a number in the range 1--366; most importantly, it does not change by locale as per DATEPART(weekday, ...) & SET DATEFIRST.]
EDIT: Why dayofyear goes wrong: As user #AeroX has commented, if the birth/start date is after February in a non leap year, the age is incremented one day early when the current/end date is a leap year, e.g. '2015-05-26', '2016-05-25' gives an age of 1 when it should still be 0. Comparing the dayofyear in different years is clearly dangerous. So using MONTH() and DAY() is necessary after all.

I believe this is similar to other ones posted here.... but this solution worked for the leap year examples 02/29/1976 to 03/01/2011 and also worked for the case for the first year.. like 07/04/2011 to 07/03/2012 which the last one posted about leap year solution did not work for that first year use case.
SELECT FLOOR(DATEDIFF(DAY, #date1 , #date2) / 365.25)
Found here.

Since there isn't one simple answer that always gives the correct age, here's what I came up with.
SELECT DATEDIFF(YY, DateOfBirth, GETDATE()) -
CASE WHEN RIGHT(CONVERT(VARCHAR(6), GETDATE(), 12), 4) >=
RIGHT(CONVERT(VARCHAR(6), DateOfBirth, 12), 4)
THEN 0 ELSE 1 END AS AGE
This gets the year difference between the birth date and the current date. Then it subtracts a year if the birthdate hasn't passed yet.
Accurate all the time - regardless of leap years or how close to the birthdate.
Best of all - no function.

I've done a lot of thinking and searching about this and I have 3 solutions that
calculate age correctly
are short (mostly)
are (mostly) very understandable.
Here are testing values:
DECLARE #NOW DATETIME = '2013-07-04 23:59:59'
DECLARE #DOB DATETIME = '1986-07-05'
Solution 1: I found this approach in one js library. It's my favourite.
DATEDIFF(YY, #DOB, #NOW) -
CASE WHEN DATEADD(YY, DATEDIFF(YY, #DOB, #NOW), #DOB) > #NOW THEN 1 ELSE 0 END
It's actually adding difference in years to DOB and if it is bigger than current date then subtracts one year. Simple right? The only thing is that difference in years is duplicated here.
But if you don't need to use it inline you can write it like this:
DECLARE #AGE INT = DATEDIFF(YY, #DOB, #NOW)
IF DATEADD(YY, #AGE, #DOB) > #NOW
SET #AGE = #AGE - 1
Solution 2: This one I originally copied from #bacon-bits. It's the easiest to understand but a bit long.
DATEDIFF(YY, #DOB, #NOW) -
CASE WHEN MONTH(#DOB) > MONTH(#NOW)
OR MONTH(#DOB) = MONTH(#NOW) AND DAY(#DOB) > DAY(#NOW)
THEN 1 ELSE 0 END
It's basically calculating age as we humans do.
Solution 3: My friend refactored it into this:
DATEDIFF(YY, #DOB, #NOW) -
CEILING(0.5 * SIGN((MONTH(#DOB) - MONTH(#NOW)) * 50 + DAY(#DOB) - DAY(#NOW)))
This one is the shortest but it's most difficult to understand. 50 is just a weight so the day difference is only important when months are the same. SIGN function is for transforming whatever value it gets to -1, 0 or 1. CEILING(0.5 * is the same as Math.max(0, value) but there is no such thing in SQL.

What about:
DECLARE #DOB datetime
SET #DOB='19851125'
SELECT Datepart(yy,convert(date,GETDATE())-#DOB)-1900
Wouldn't that avoid all those rounding, truncating and ofsetting issues?

Just check whether the below answer is feasible.
DECLARE #BirthDate DATE = '09/06/1979'
SELECT
(
YEAR(GETDATE()) - YEAR(#BirthDate) -
CASE WHEN (MONTH(GETDATE()) * 100) + DATEPART(dd, GETDATE()) >
(MONTH(#BirthDate) * 100) + DATEPART(dd, #BirthDate)
THEN 1
ELSE 0
END
)

select floor((datediff(day,0,#today) - datediff(day,0,#birthdate)) / 365.2425) as age
There are a lot of 365.25 answers here. Remember how leap years are defined:
Every four years
except every 100 years
except every 400 years

There are many answers to this question, but I think this one is close to the truth.
The datediff(year,…,…) function, as we all know, only counts the boundaries crossed by the date part, in this case the year. As a result it ignores the rest of the year.
This will only give the age in completed years if the year were to start on the birthday. It probably doesn’t, but we can fake it by adjusting the asking date back by the same amount.
In pseudopseudo code, it’s something like this:
adjusted_today = today - month(dob) + 1 - day(dob) + 1
age = year(adjusted_today - dob)
The + 1 is to allow for the fact that the month and day numbers start from 1 and not 0.
The reason we subtract the month and the day separately rather than the day of the year is because February has the annoying tendency to change its length.
The calculation in SQL is:
datediff(year,dob,dateadd(month,-month(dob)+1,dateadd(day,-day(dob)+1,today)))
where dob and today are presumed to be the date of birth and the asking date.
You can test this as follows:
WITH dates AS (
SELECT
cast('2022-03-01' as date) AS today,
cast('1943-02-25' as date) AS dob
)
select
datediff(year,dob,dateadd(month,-month(dob)+1,dateadd(day,-day(dob)+1,today))) AS age
from dates;
which gives you George Harrison’s age in completed years.
This is much cleaner than fiddling about with quarter days which will generally give you misleading values on the edges.
If you have the luxury of creating a scalar function, you can use something like this:
DROP FUNCTION IF EXISTS age;
GO
CREATE FUNCTION age(#dob date, #today date) RETURNS INT AS
BEGIN
SET #today = dateadd(month,-month(#dob)+1,#today);
SET #today = dateadd(day,-day(#dob)+1,#today);
RETURN datediff(year,#dob,#today);
END;
GO
Remember, you need to call dbo.age() because, well, Microsoft.

DECLARE #DOB datetime
set #DOB ='11/25/1985'
select floor(
( cast(convert(varchar(8),getdate(),112) as int)-
cast(convert(varchar(8),#DOB,112) as int) ) / 10000
)
source: http://beginsql.wordpress.com/2012/04/26/how-to-calculate-age-in-sql-server/

Try This
DECLARE #date datetime, #tmpdate datetime, #years int, #months int, #days int
SELECT #date = '08/16/84'
SELECT #tmpdate = #date
SELECT #years = DATEDIFF(yy, #tmpdate, GETDATE()) - CASE WHEN (MONTH(#date) > MONTH(GETDATE())) OR (MONTH(#date) = MONTH(GETDATE()) AND DAY(#date) > DAY(GETDATE())) THEN 1 ELSE 0 END
SELECT #tmpdate = DATEADD(yy, #years, #tmpdate)
SELECT #months = DATEDIFF(m, #tmpdate, GETDATE()) - CASE WHEN DAY(#date) > DAY(GETDATE()) THEN 1 ELSE 0 END
SELECT #tmpdate = DATEADD(m, #months, #tmpdate)
SELECT #days = DATEDIFF(d, #tmpdate, GETDATE())
SELECT Convert(Varchar(Max),#years)+' Years '+ Convert(Varchar(max),#months) + ' Months '+Convert(Varchar(Max), #days)+'days'

After trying MANY methods, this works 100% of the time using the modern MS SQL FORMAT function instead of convert to style 112. Either would work but this is the least code.
Can anyone find a date combination which does not work? I don't think there is one :)
--Set parameters, or choose from table.column instead:
DECLARE #DOB DATE = '2000/02/29' -- If #DOB is a leap day...
,#ToDate DATE = '2018/03/01' --...there birthday in this calculation will be
--0+ part tells SQL to calc the char(8) as numbers:
SELECT [Age] = (0+ FORMAT(#ToDate,'yyyyMMdd') - FORMAT(#DOB,'yyyyMMdd') ) /10000

CASE WHEN datepart(MM, getdate()) < datepart(MM, BIRTHDATE) THEN ((datepart(YYYY, getdate()) - datepart(YYYY, BIRTH_DATE)) -1 )
ELSE
CASE WHEN datepart(MM, getdate()) = datepart(MM, BIRTHDATE)
THEN
CASE WHEN datepart(DD, getdate()) < datepart(DD, BIRTHDATE) THEN ((datepart(YYYY, getdate()) - datepart(YYYY, BIRTHDATE)) -1 )
ELSE (datepart(YYYY, getdate()) - datepart(YYYY, BIRTHDATE))
END
ELSE (datepart(YYYY, getdate()) - datepart(YYYY, BIRTHDATE)) END
END

SELECT ID,
Name,
DATEDIFF(yy,CONVERT(DATETIME, DOB),GETDATE()) AS AGE,
DOB
FROM MyTable

How about this:
SET #Age = CAST(DATEDIFF(Year, #DOB, #Stamp) as int)
IF (CAST(DATEDIFF(DAY, DATEADD(Year, #Age, #DOB), #Stamp) as int) < 0)
SET #Age = #Age - 1

Try this solution:
declare #BirthDate datetime
declare #ToDate datetime
set #BirthDate = '1/3/1990'
set #ToDate = '1/2/2008'
select #BirthDate [Date of Birth], #ToDate [ToDate],(case when (DatePart(mm,#ToDate) < Datepart(mm,#BirthDate))
OR (DatePart(m,#ToDate) = Datepart(m,#BirthDate) AND DatePart(dd,#ToDate) < Datepart(dd,#BirthDate))
then (Datepart(yy, #ToDate) - Datepart(yy, #BirthDate) - 1)
else (Datepart(yy, #ToDate) - Datepart(yy, #BirthDate))end) Age

This will correctly handle the issues with the birthday and rounding:
DECLARE #dob datetime
SET #dob='1992-01-09 00:00:00'
SELECT DATEDIFF(YEAR, '0:0', getdate()-#dob)

Ed Harper's solution is the simplest I have found which never returns the wrong answer when the month and day of the two dates are 1 or less days apart. I made a slight modification to handle negative ages.
DECLARE #D1 AS DATETIME, #D2 AS DATETIME
SET #D2 = '2012-03-01 10:00:02'
SET #D1 = '2013-03-01 10:00:01'
SELECT
DATEDIFF(YEAR, #D1,#D2)
+
CASE
WHEN #D1<#D2 AND DATEADD(YEAR, DATEDIFF(YEAR,#D1, #D2), #D1) > #D2
THEN - 1
WHEN #D1>#D2 AND DATEADD(YEAR, DATEDIFF(YEAR,#D1, #D2), #D1) < #D2
THEN 1
ELSE 0
END AS AGE

The answer marked as correct is nearer to accuracy but, it fails in following scenario - where Year of birth is Leap year and day are after February month
declare #ReportStartDate datetime = CONVERT(datetime, '1/1/2014'),
#DateofBirth datetime = CONVERT(datetime, '2/29/1948')
FLOOR(DATEDIFF(HOUR,#DateofBirth,#ReportStartDate )/8766)
OR
FLOOR(DATEDIFF(HOUR,#DateofBirth,#ReportStartDate )/8765.82) -- Divisor is more accurate than 8766
-- Following solution is giving me more accurate results.
FLOOR(DATEDIFF(YEAR,#DateofBirth,#ReportStartDate) - (CASE WHEN DATEADD(YY,DATEDIFF(YEAR,#DateofBirth,#ReportStartDate),#DateofBirth) > #ReportStartDate THEN 1 ELSE 0 END ))
It worked in almost all scenarios, considering leap year, date as 29 feb, etc.
Please correct me if this formula have any loophole.

Declare #dob datetime
Declare #today datetime
Set #dob = '05/20/2000'
set #today = getdate()
select CASE
WHEN dateadd(year, datediff (year, #dob, #today), #dob) > #today
THEN datediff (year, #dob, #today) - 1
ELSE datediff (year, #dob, #today)
END as Age

Here is how i calculate age given a birth date and current date.
select case
when cast(getdate() as date) = cast(dateadd(year, (datediff(year, '1996-09-09', getdate())), '1996-09-09') as date)
then dateDiff(yyyy,'1996-09-09',dateadd(year, 0, getdate()))
else dateDiff(yyyy,'1996-09-09',dateadd(year, -1, getdate()))
end as MemberAge
go

CREATE function dbo.AgeAtDate(
#DOB datetime,
#CompareDate datetime
)
returns INT
as
begin
return CASE WHEN #DOB is null
THEN
null
ELSE
DateDiff(yy,#DOB, #CompareDate)
- CASE WHEN datepart(mm,#CompareDate) > datepart(mm,#DOB) OR (datepart(mm,#CompareDate) = datepart(mm,#DOB) AND datepart(dd,#CompareDate) >= datepart(dd,#DOB))
THEN 0
ELSE 1
END
END
End
GO

DECLARE #FromDate DATETIME = '1992-01-2623:59:59.000',
#ToDate DATETIME = '2016-08-10 00:00:00.000',
#Years INT, #Months INT, #Days INT, #tmpFromDate DATETIME
SET #Years = DATEDIFF(YEAR, #FromDate, #ToDate)
- (CASE WHEN DATEADD(YEAR, DATEDIFF(YEAR, #FromDate, #ToDate),
#FromDate) > #ToDate THEN 1 ELSE 0 END)
SET #tmpFromDate = DATEADD(YEAR, #Years , #FromDate)
SET #Months = DATEDIFF(MONTH, #tmpFromDate, #ToDate)
- (CASE WHEN DATEADD(MONTH,DATEDIFF(MONTH, #tmpFromDate, #ToDate),
#tmpFromDate) > #ToDate THEN 1 ELSE 0 END)
SET #tmpFromDate = DATEADD(MONTH, #Months , #tmpFromDate)
SET #Days = DATEDIFF(DAY, #tmpFromDate, #ToDate)
- (CASE WHEN DATEADD(DAY, DATEDIFF(DAY, #tmpFromDate, #ToDate),
#tmpFromDate) > #ToDate THEN 1 ELSE 0 END)
SELECT #FromDate FromDate, #ToDate ToDate,
#Years Years, #Months Months, #Days Days

What about a solution with only date functions, not math, not worries about leap year
CREATE FUNCTION dbo.getAge(#dt datetime)
RETURNS int
AS
BEGIN
RETURN
DATEDIFF(yy, #dt, getdate())
- CASE
WHEN
MONTH(#dt) > MONTH(GETDATE()) OR
(MONTH(#dt) = MONTH(GETDATE()) AND DAY(#dt) > DAY(GETDATE()))
THEN 1
ELSE 0
END
END

declare #birthday as datetime
set #birthday = '2000-01-01'
declare #today as datetime
set #today = GetDate()
select
case when ( substring(convert(varchar, #today, 112), 5,4) >= substring(convert(varchar, #birthday, 112), 5,4) ) then
(datepart(year,#today) - datepart(year,#birthday))
else
(datepart(year,#today) - datepart(year,#birthday)) - 1
end

The following script checks the difference in years between now and the given date of birth; the second part checks whether the birthday is already past in the current year; if not, it subtracts it:
SELECT year(NOW()) - year(date_of_birth) - (CONCAT(year(NOW()), '-', month(date_of_birth), '-', day(date_of_birth)) > NOW()) AS Age
FROM tableName;

Extract full weeks and remaining days from date range in SQL

I have a date range say 1-Jul-2016 to 10-Jul-2016. I want to extract number of weeks and remaining days exists in that range like
No. of Weeks = 1
No. of Remaining Days = 3
I know how to find days OR week difference using
DATEDIFF(DAY,#ArrivalDate,#DepartureDate)
DATEDIFF(WEEK,#ArrivalDate,#DepartureDate)
But how to find and get whether a date contains only full Weeks or Weeks and Days.
Any help will be highly appreciated.

Try following query
DECLARE #StartDate DATETIME = '2016.07.01'
DECLARE #EndDate DATETIME = '2016.07.10'
SELECT
DATEDIFF(DAY, #StartDate, #EndDate) / 7 AS 'No. of Weeks', -- 1
(DATEDIFF(DAY, #StartDate, #EndDate) % 7) + 1 AS 'No. of Remaining Days' -- 3

DECLARE #StartDate DATETIME = '2016.07.01'
DECLARE #EndDate DATETIME = '2016.07.10'
SELECT
-- DATEDIFF(DAY, #StartDate, #EndDate) / 7 AS 'No. of Weeks', -- 1
DATEDIFF(WEEK, #StartDate, #EndDate) AS 'No. of Weeks',
(DATEDIFF(DAY, #StartDate, #EndDate) % 7) + 1 AS 'No. of Remaining Days' -- 3

count week days in sql by datediff [duplicate]

This question already has answers here:
Count work days between two dates
(24 answers)
Calculating days to excluding weekends (Monday to Friday) in SQL Server
(6 answers)
Closed 7 years ago.
I'm looking for a way to calculate the days between two dates, but on weekdays. Here is the formula, but it counts weekend days.
DATEDIFF(DAY,STARTDATE,ENDDATE)
SELECT DATEDIFF(DAY,'2015/06/01' , '2015/06/30')
Result of above query of datediff is 29 days which are weekend days. but i need week days that should be 21 by removing Saturday and Sunday(8 days).
Any suggestions?

Put it in the WHERE clause
SELECT DATEDIFF(DAY,'2015/06/01' , '2015/06/30')
FROM yourtable
WHERE DATENAME(dw, StartDate) != 'Saturday'
AND DATENAME(dw, StartDate) != 'Sunday'
Or all in a SELECT statement
SELECT (DATEDIFF(dd, StartDate, EndDate) + 1)-(DATEDIFF(wk, StartDate, EndDate) * 2)-(CASE WHEN DATENAME(dw, StartDate) = 'Sunday' THEN 1 ELSE 0 END)-(CASE WHEN DATENAME(dw, EndDate) = 'Saturday' THEN 1 ELSE 0 END)

This returns 22:
DECLARE #StartDate AS DATE = '20150601'
DECLARE #EndDate AS DATE = '20150630'
SELECT
(DATEDIFF(DAY, #StartDate, #EndDate))
-(DATEDIFF(WEEK, #StartDate, #EndDate) * 2)
-(CASE WHEN DATENAME(dw, #StartDate) = 'Sunday' THEN 1 ELSE 0 END)
-(CASE WHEN DATENAME(dw, #EndDate) = 'Saturday' THEN 1 ELSE 0 END)
Read this article by Jeff Moden for more information.
Explanation:
First, (DATEDIFF(DAY, #StartDate, #EndDate)) will return the difference in number of days. In this case, it'll be 29. Now, depending on your interpretation of whole days, you may want to add 1 day to its result.
Next,(DATEDIFF(WEEK, #StartDate, #EndDate) * 2):
To quote the article:
DATEDIFF for the WEEK datepart doesn't actually calculate weeks, it
calculates the number of times a date range contains dates that
represent pairs of Saturdays and Sundays. To think of it in more
simple terms, it only counts WHOLE WEEKENDS!
So, to exclude the weekends, you must subtract twice the result of this from the first DATEDIFF. Which now will be: 29 - (2 *4) = 21.
Finally, this:
-(CASE WHEN DATENAME(dw, #StartDate) = 'Sunday' THEN 1 ELSE 0 END)
-(CASE WHEN DATENAME(dw, #EndDate) = 'Saturday' THEN 1 ELSE 0 END)
removes the partial weeks, which only happens when then #StartDate occurs on a Sunday and the #EndDate occurs on a Saturday.

You can try recursive cte:
WITH cte
AS ( SELECT CAST('2015/06/01' AS DATE) AS dt ,
DATEPART(WEEKDAY, '2015/06/01') AS wd
UNION ALL
SELECT DATEADD(d, 1, dt) AS dt ,
DATEPART(WEEKDAY, DATEADD(d, 1, dt))
FROM cte
WHERE dt < '2015/06/30'
)
SELECT COUNT(*)
FROM cte
WHERE wd NOT IN ( 7, 1 )
Result is 22.
You better add some useful calendar table that every database should have. Fill it with some big range and then use it to calculate business days.

I wrote a simple stored procedure - don't know if a SP is what you need but i think you can easily convert it to a function , TVF, whatever:
CREATE PROCEDURE [dbo].[BusinessdaysBetween](#DateFrom DATE, #DateTo DATE, #days INT OUTPUT)
AS
BEGIN
DECLARE #datefirst INT = ##DATEFIRST
SET DATEFIRST 1 --so week starts on monday
SET #days = 0
IF #DateFrom > #DateTo
RETURN NULL
IF #DateFrom = #DateTo
RETURN #days
WHILE #DateFrom <= #DateTo
BEGIN
IF DATEPART(WEEKDAY,#DateFrom) NOT IN (6,7) --Saturday or Sunday
BEGIN
SET #days = #days + 1
END
SET #DateFrom = DATEADD(DAY,1,#DateFrom)
END
SET DATEFIRST #datefirst --restore original setup
END
GO
in my example i call i it like this:
DECLARE #days INT = 0
DECLARE #datefrom DATETIME = GETDATE()
DECLARE #dateto DATETIME = DATEADD(DAY,25,GETDATE())
EXEC dbo.BusinessdaysBetween #datefrom, #dateto, #days OUTPUT
SELECT #days

How to filter my results so it shows the last four months of data - sql

I'm trying to create a stored procedure that gets the last 4 months worth of results from the below query but I'm unsure how to do this.
This is what I have done so far:
Declare #Number varchar(30) = '12'
Select
month = month(EndDate),
YEAR = YEAR(EndDate),
SUM(DownloadUnits) as downloads,
SUM(UploadUnits) as uploads,
number
from testTable
where number=#Number
GROUP BY MONTH(EndDate), Year(Enddate),number
How can I filter it out so that when I pass month parameter (I haven't created it yet) it filters out the results so it only shows the last four months? (I have hard coded the number parameter for testing)

The last N months from now meet the condition
where EndDate >= dateadd(month, -#DEDUCT_MONTHS, cast(getdate() as DATE))
Removing the cast will enforce the current time as a constraint as opposed to midnight N months ago.

If you need to get whole months then you will need to get the first of the month 4 months ago.
You can get the first of the current month using:
SELECT DATEADD(MONTH, DATEDIFF(MONTH, '19000101', GETDATE()), '19000101');
Adapting this slightly will give you the first of the month 4 months ago:
SELECT DATEADD(MONTH, DATEDIFF(MONTH, '19000101', GETDATE()) - 4, '19000101');
Then you can just apply this filter to your query:
WHERE EndDate >= DATEADD(MONTH, DATEDIFF(MONTH, '19000101', GETDATE()) - 4, '19000101')
Or if you need to pass the number of months a parameter (it should be an INT not a varchar by the way):
WHERE EndDate >= DATEADD(MONTH, DATEDIFF(MONTH, '19000101', GETDATE()) - #Number, '19000101')
If you pass a date parameter, just replace GETDATE() with your parameter name.

DECLARE #StartDate date
SET #StartDate=Dateadd(Month, Datediff(Month, 0, DATEADD(m, -6, getdate())), 0)
--first day of the month, (current month-6 month)
The script above will return with the first day of the month - 6 month ago .
This solution is from stackoverflow somewhere, unfortunately I dont seem to find the original post.. :(
To understand how it works try to reverse-engineer as per follows:
DECLARE #StartDate1 date
SET #StartDate1= DATEADD(m, -6, getdate())
PRINT #Startdate1
DECLARE #StartDate2 int
SET #StartDate2= Datediff(Month, 0, DATEADD(m, -6, getdate()))
PRINT #Startdate2
DECLARE #StartDate3 date
SET #StartDate3=Dateadd(Month, 1369, 0)
PRINT #Startdate3

Get the records of last month in SQL server

I want to get the records of last month based on my db table [member] field "date_created".
What's the sql to do this?
For clarification,
last month - 1/8/2009 to 31/8/2009
If today is 3/1/2010, I'll need to get the records of 1/12/2009 to 31/12/2009.

All the existing (working) answers have one of two problems:
They will ignore indices on the column being searched
The will (potentially) select data that is not intended, silently corrupting your results.
1. Ignored Indices:
For the most part, when a column being searched has a function called on it (including implicitly, like for CAST), the optimizer must ignore indices on the column and search through every record. Here's a quick example:
We're dealing with timestamps, and most RDBMSs tend to store this information as an increasing value of some sort, usually a long or BIGINTEGER count of milli-/nanoseconds. The current time thus looks/is stored like this:
1402401635000000 -- 2014-06-10 12:00:35.000000 GMT
You don't see the 'Year' value ('2014') in there, do you? In fact, there's a fair bit of complicated math to translate back and forth. So if you call any of the extraction/date part functions on the searched column, the server has to perform all that math just to figure out if you can include it in the results. On small tables this isn't an issue, but as the percentage of rows selected decreases this becomes a larger and larger drain. Then in this case, you're doing it a second time for asking about MONTH... well, you get the picture.
2. Unintended data:
Depending on the particular version of SQL Server, and column datatypes, using BETWEEN (or similar inclusive upper-bound ranges: <=) can result in the wrong data being selected. Essentially, you potentially end up including data from midnight of the "next" day, or excluding some portion of the "current" day's records.
What you should be doing:
So we need a way that's safe for our data, and will use indices (if viable). The correct way is then of the form:
WHERE date_created >= #startOfPreviousMonth AND date_created < #startOfCurrentMonth
Given that there's only one month, #startOfPreviousMonth can be easily substituted for/derived by:
DATEADD(month, -1, #startOfCurrentMonth)
If you need to derive the start-of-current-month in the server, you can do it via the following:
DATEADD(month, DATEDIFF(month, 0, CURRENT_TIMESTAMP), 0)
A quick word of explanation here. The initial DATEDIFF(...) will get the difference between the start of the current era (0001-01-01 - AD, CE, whatever), essentially returning a large integer. This is the count of months to the start of the current month. We then add this number to the start of the era, which is at the start of the given month.
So your full script could/should look similar to the following:
DECLARE #startOfCurrentMonth DATETIME
SET #startOfCurrentMonth = DATEADD(month, DATEDIFF(month, 0, CURRENT_TIMESTAMP), 0)
SELECT *
FROM Member
WHERE date_created >= DATEADD(month, -1, #startOfCurrentMonth)
AND date_created < #startOfCurrentMonth
All date operations are thus only performed once, on one value; the optimizer is free to use indices, and no incorrect data will be included.

SELECT *
FROM Member
WHERE DATEPART(m, date_created) = DATEPART(m, DATEADD(m, -1, getdate()))
AND DATEPART(yyyy, date_created) = DATEPART(yyyy, DATEADD(m, -1, getdate()))
You need to check the month and year.

Add the options which have been provided so far won't use your indexes at all.
Something like this will do the trick, and make use of an index on the table (if one exists).
DECLARE #StartDate DATETIME, #EndDate DATETIME
SET #StartDate = dateadd(mm, -1, getdate())
SET #StartDate = dateadd(dd, datepart(dd, getdate())*-1, #StartDate)
SET #EndDate = dateadd(mm, 1, #StartDate)
SELECT *
FROM Member
WHERE date_created BETWEEN #StartDate AND #EndDate

DECLARE #StartDate DATETIME, #EndDate DATETIME
SET #StartDate = DATEADD(mm, DATEDIFF(mm,0,getdate())-1, 0)
SET #EndDate = DATEADD(mm, 1, #StartDate)
SELECT *
FROM Member
WHERE date_created BETWEEN #StartDate AND #EndDate
An upgrade to mrdenny's solution, this way you get exactly last month from YYYY-MM-01

Last month consider as till last day of the month.
31/01/2016 here last day of the month would be 31 Jan. which is not similar to last 30 days.
SELECT CONVERT(DATE, DATEADD(DAY,-DAY(GETDATE()),GETDATE()))

One way to do it is using the DATEPART function:
select field1, field2, fieldN from TABLE where DATEPART(month, date_created) = 4
and DATEPART(year, date_created) = 2009
will return all dates in april. For last month (ie, previous to current month) you can use GETDATE and DATEADD as well:
select field1, field2, fieldN from TABLE where DATEPART(month, date_created)
= (DATEPART(month, GETDATE()) - 1) and
DATEPART(year, date_created) = DATEPART(year, DATEADD(m, -1, GETDATE()))

declare #PrevMonth as nvarchar(256)
SELECT #PrevMonth = DateName( month,DATEADD(mm, DATEDIFF(mm, 0, getdate()) - 1, 0)) +
'-' + substring(DateName( Year, getDate() ) ,3,4)

SQL query to get record of the present month only
SELECT * FROM CUSTOMER
WHERE MONTH(DATE) = MONTH(CURRENT_TIMESTAMP) AND YEAR(DATE) = YEAR(CURRENT_TIMESTAMP);

SELECT * FROM Member WHERE month(date_created) = month(NOW() - INTERVAL 1 MONTH);

select * from [member] where DatePart("m", date_created) = DatePart("m", DateAdd("m", -1, getdate())) AND DatePart("yyyy", date_created) = DatePart("yyyy", DateAdd("m", -1, getdate()))

DECLARE #StartDate DATETIME, #EndDate DATETIME
SET #StartDate = DATEADD(mm, DATEDIFF(mm, 0, getdate()) - 1, 0)
SET #EndDate = dateadd(dd, -1, DATEADD(mm, 1, #StartDate))
SELECT * FROM Member WHERE date_created BETWEEN #StartDate AND #EndDate
and another upgrade to mrdenny's solution.
It gives the exact last day of the previous month as well.

WHERE
date_created >= DATEADD(MONTH, DATEDIFF(MONTH, 31, CURRENT_TIMESTAMP), 0)
AND date_created < DATEADD(MONTH, DATEDIFF(MONTH, 0, CURRENT_TIMESTAMP), 0)

I'm from Oracle env and I would do it like this in Oracle:
select * from table
where trunc(somedatefield, 'MONTH') =
trunc(sysdate -INTERVAL '0-1' YEAR TO MONTH, 'MONTH')
Idea: I'm running a scheduled report of previous month (from day 1 to the last day of the month, not windowed). This could be index unfriendly, but Oracle has fast date handling anyways.
Is there a similar simple and short way in MS SQL? The answer comparing year and month separately seems silly to Oracle folks.

You can get the last month records with this query
SELECT * FROM dbo.member d
WHERE CONVERT(DATE, date_created,101)>=CONVERT(DATE,DATEADD(m, datediff(m, 0, current_timestamp)-1, 0))
and CONVERT(DATE, date_created,101) < CONVERT(DATE, DATEADD(m, datediff(m, 0, current_timestamp)-1, 0),101)

I don't think the accepted solution is very index friendly
I use the following lines instead
select * from dbtable where the_date >= convert(varchar(10),DATEADD(m, -1, dateadd(d, - datepart(dd, GETDATE())+1, GETDATE())),120) and the_date <= dateadd(ms, -3, convert(varchar(10),DATEADD(m, 0, dateadd(d, - datepart(dd, GETDATE())+1, GETDATE())),120));
Or simply (this is the best).
select * from dbtable where the_date >= convert(varchar(10),DATEADD(m, -1, dateadd(d, - datepart(dd, GETDATE())+1, GETDATE())),120) and the_date < SELECT convert(varchar(10),DATEADD(m, -1, dateadd(d, - datepart(dd, GETDATE())+1, GETDATE())),120);
Some help
-- Get the first of last month
SELECT convert(varchar(10),DATEADD(m, -1, dateadd(d, - datepart(dd, GETDATE())+1, GETDATE())),120);
-- Get the first of current month
SELECT convert(varchar(10),DATEADD(m, -1, dateadd(d, - datepart(dd, GETDATE())+1, GETDATE())),120);
--Get the last of last month except the last 3milli seconds. (3miliseconds being used as SQL express otherwise round it up to the full second (SERIUSLY MS)
SELECT dateadd(ms, -3, convert(varchar(10),DATEADD(m, 0, dateadd(d, - datepart(dd, GETDATE())+1, GETDATE())),120));

Here is what I did so I could put it in a view:
ALTER view [dbo].[MyView] as
with justdate as (
select getdate() as rightnow
)
, inputs as (
select dateadd(day, 1, EOMONTH(jd.rightnow, -2)) as FirstOfLastMonth
,dateadd(day, 1, EOMONTH(jd.rightnow, -1)) as FirstOfThisMonth
from justdate jd
)
SELECT TOP 10000
[SomeColumn]
,[CreatedTime]
from inputs i
join [dbo].[SomeTable]
on createdtime >= i.FirstOfLastMonth
and createdtime < i.FirstOfThisMonth
order by createdtime
;
Note that I intentionally ran getdate() once.

In Sql server for last one month:
select * from tablename
where order_date > DateAdd(WEEK, -1, GETDATE()+1) and order_date<=GETDATE()

DECLARE #curDate INT = datepart( Month,GETDATE())
IF (#curDate = 1)
BEGIN
select * from Featured_Deal
where datepart( Month,Created_Date)=12 AND datepart(Year,Created_Date) = (datepart(Year,GETDATE())-1)
END
ELSE
BEGIN
select * from Featured_Deal
where datepart( Month,Created_Date)=(datepart( Month,GETDATE())-1) AND datepart(Year,Created_Date) = datepart(Year,GETDATE())
END

DECLARE #StartDate DATETIME, #EndDate DATETIME
SET #StartDate = dateadd(mm, -1, getdate())
SET #StartDate = dateadd(dd, datepart(dd, getdate())*-1, #StartDate)
SET #EndDate = dateadd(mm, 1, #StartDate)
set #StartDate = DATEADD(dd, 1 , #StartDate)

The way I fixed similar issue was by adding Month to my SELECT portion
Month DATEADD(day,Created_Date,'1971/12/31') As Month
and than I added WHERE statement
Month DATEADD(day,Created_Date,'1971/12/31') = month(getdate())-1

If you are looking for last month so try this,
SELECT
FROM #emp
WHERE DATEDIFF(MONTH,CREATEDDATE,GETDATE()) = 1
If you are looking for last month so try this,
SELECT
FROM #emp
WHERE DATEDIFF(day,CREATEDDATE,GETDATE()) between 1 and 30

A simple query which works for me is:
select * from table where DATEADD(month, 1,DATEFIELD) >= getdate()

If you are looking for previous month data:
date(date_created)>=date_sub(date_format(curdate(),"%Y-%m-01"),interval 1 month) and
date(date_created)<=date_sub(date_format(curdate(),'%Y-%m-01'),interval 1 day)
This will also work when the year changes. It will also work on MySQL.