I need to query SQL for data that falls into a last month date. I thought I was using the correct query logic but I get no results and I know there are results. The snippet of code is this:
MONTH(n.JOIN_DATE) = DATEADD(month, - 1, GETDATE())
This is giving me no results and I need to get anyone who has a join date of last month. What am I missing?
Use this:
MONTH(n.JOIN_DATE) = MONTH(DATEADD(month, - 1, GETDATE()))
You need to compare apples with apples, so compare the numerical month on both sides of the equation.
Massive credit to #PaulL for figuring this out before I did.
Update:
As #DasBlinkenLight and Matt pointed out, just comparing by month leaves the door open for multiple years to be returned. One possible fix would be to also compare the years, e.g.
WHERE MONTH(n.JOIN_DATE) = MONTH(DATEADD(month, - 1, GETDATE())) AND
YEAR(n.JOIN_DATE) = YEAR(DATEADD(month, - 1, GETDATE()))
MONTH(...) produces a month number. You should not compare it to the result returned by DATEADD, which is actually a date.
If you are looking for everyone who has joined less than a month ago, you can do it like this:
WHERE DATEADD(month, 1, n.JOIN_DATE) > GETDATE()
This takes into account the year and the day as well, not only the month.
If you are looking for everyone who joined last month, no matter on what day, you can use a more complex condition:
WHERE MONTH(DATEADD(month, -1, GETDATE()) = MONTH(n.JOIN_DATE)
AND YEAR (DATEADD(month, -1, GETDATE()) = YEAR (n.JOIN_DATE)
The second condition is necessary to avoid confusion between members joining last month and members joining on the same month one or more years ago.
MONTH(n.JOIN_DATE) returns a numeric which indicate the month in date m.JOIN_DATE
DATEADD(month, - 1, GETDATE()) returns a date which indicate date in last month.
So, you can use this instead :
MONTH(n.JOIN_DATE)= MONTH(DATEADD(month, - 1, GETDATE()))
OR
n.JOIN_DATE = DATEADD(month, - 1, GETDATE())
MONTH(n.JOIN_DATE) will only return the numerical value of the month (e.g.: 11 or 5).
DATEADD(MONTH, -1, GETDATE()) will simply subtract one month from the current date. It is still in a DATETIME format.
You may be looking for:
MONTH(n.JOIN_DATE) = MONTH(DATEADD(MONTH, -1, GETDATE()))
SELECT
DATEFROMPARTS(YEAR(DATEADD(month,-1,GETDATE())),MONTH(DATEADD(month,-1,GETDATE())),1) AS StartOfLastMonth
,DATEADD(day,-1,(DATEFROMPARTS(YEAR(GETDATE()),MONTH(GETDATE()),1))) AS EndOfLastMonthAsDate
,DATEADD(day,-3,CAST(DATEFROMPARTS(YEAR(GETDATE()),MONTH(GETDATE()),1) AS DATETIME)) AS EndOfLastMonthMidngith
,CAST(DATEADD(month,-1,GETDATE()) AS DATE) AS OneMonthAgoStrartOfDay
,CAST(GETDATE() AS DATE) AS StartOfToday
,DATEADD(MS,-3,CAST(CAST(GETDATE() AS DATE) AS DATETIME)) AS MidnightLastNight
Okay As people have definitely illustrated there are a lot of different answers to your question and all are built upon similar premise. using DATEADD() with a negative number to go back a month. Or to compare month and year to see if they are the same. The former being geared at 1 month ago to today and the later being last month.
All of the answers so far, expect #DasBlinkenLight and #TimBiegeleisen, fail to take into account TIME component of your column and the GETDATE() function if you have one. If your column is DATETIME you will need to take that into account. The above SELECT query that will arm you with some ways of getting to different dates that i suspect will meet your needs.
As far as using BETWEEN with dates be careful! because the values you put in are inclusive so if you put GETDATE() on the right side of the between statement you will get today's results too but you might really want UP TO to today in which case you should change your right side argument. Also I am not sure about Oracle, mysql, etc. but Micrsofot SQL-Server is accurate to .003 milliseconds. So if you really want to look at midnight of a date you should look at 23:59:59.997 because .998 and .999 will round up to the next day.
Also to further simplify if you don't want time components you can also cast your column to DATE and it essentially drops off the time and the BETWEEN because a little clearer too, e.g. CAST(n.JOIN_DATE AS DATE)
There are definitely other questions on this subject on stackoverflow I encourage you to research.
I knew this was a simple one and I was missing something to it. My code was wrong based upon the many responses I received on this and I was comparing apples to oranges and not apples to apples. Once I added the Month() around the dateadd function, it worked.
The reply to this answer are correct. But in the light of best practice writing your query this way will make it less SARGABLE, hence making it ignore indexes if you have one. It might be better to write it as
WHERE n.JOIN_DATE between DATEADD(MONTH, DATEDIFF(MONTH, 0, GETDATE())-1, 0) AND DATEADD(MONTH, DATEDIFF(MONTH, -1, GETDATE())-1, -1)
based on the comment below I have modified the query. I guess I did not read the question in depth.
Related
I'm running the following query
SELECT a.DAT
FROM a
and getting a column of datetimes. I would like to change this column or alternatively add a column, that adds a workday to the corresponding datetime and I want to be able to filter for the date at the same time
My approach for changing the workday is like this CASE WHEN DATENAME(dw, date) = 'Friday' THEN DATEADD(dw, 3, date), but I don't know how to fit that in. Here I'm adding 3 days to Friday because it should skip to Monday the next workday, in the other cases I would add only 1 day, for Monday to Thursday.
Maybe there is a better way?
In this image I tried to show how the result of an examplatory query should
look like. I have all dates available but I want to filter for the 14th, which should show me the 11 dates, because of the added workday. Since June 11 is Friday
I think my Main problem is I don't know how make the extra column depending on the given datetime, it should add 3 on Fridays and 1 on every other day (Saturday and Sunday don't exist in the base data)
Thanks for your responses.
I have a solution now. If it can be easier, let me know, if you like. Anyway, thanks for your help everyone
Solution:
DECLARE #Date DATETIME
Set #Date = '14/06/2021'
SELECT
a.DAT,
(CASE WHEN DATENAME(dw, a.DAT) = 'Friday' THEN DATEADD(DAY, 3, a.DAT) ELSE DATEADD(DAY, 1, a.DAT) END) as RealDate
FROM a
WHERE (CASE WHEN DATENAME(dw, #Date) = 'Monday' THEN DATEADD(DAY, -3, #Date) ELSE DATEADD(DAY, -1, #Date) END) = a.DAT
You seem to be describing a case expression:
SELECT (CASE WHEN DATENAME(weekday, date) = 'Friday'
THEN DATEADD(DAY, 3, date)
ELSE DATEADD(DAY, 1, date)
END) as next_date
Welcome to S/O. If your table already has a datetime column, that is probably best. Dont try to break things down such as a date column, a time column, and some workday column. There are plenty of functions that allow you to extract parts as needed. However, your post tags only show SQL instead of a specific database such as sql-server, mysql, oracle, etc. but appears SQL-Server via DateAdd() function.
With date functions you could do things like filtering based on the "Day" of the given date/time column NOT being a Sat or Sun. Or, filtering on a single month by a >= first day of the month but less than first day of following month. This way you dont have to worry about time factors. This type of query would allow inclusion of working up to 11:59:59pm before following day.
If you edit your question with any additional clarifications on why adding 3 days per your example may help offer additional resolution. Try not to just put things that could be long in comments. Then just comment back on my post and I'll try to follow-up (in addition to others that may follow this post).
Currently, I am trying to run my sql query in 2 different ways.
WHERE order_date_time >= DateAdd(month,-3,getdate())
and
WHERE DATEDIFF(month,order_date_time,GetDate()) <= 3
1) Why I am getting 2 different results? Shouldn't I be getting same value as I am trying to find records from last 3 months or less?
Am I not calculating the 3 months difference correctly in my where clause?
2) Which function is better and return results faster in terms of performance?
DATEDIFF counts the number of "ticks" between 2 datetimes. So, for example DATEDIFF(MONTH,'2019-01-31T23:59:59','2019-02-01T00:00:00') returns 1, even though only 1 second has passed; the month has changed (so one "tick" has occured).
For the perspective of what is "better", that depends on your requirement, however, WHERE DATEDIFF(MONTH,order_date_time,GETDATE()) <= 3 is not advisable here, as it's non-SARGable. This is because order_date_time is contained within the function DATEDIFF.
I would use WHERE order_date_time >= DATEADD(MONTH,-3,GETDATE()) (assuming you want rows where order_date_time is in the last 3 months).
These are your conditions:
WHERE order_date_time >= DateAdd(month, -3, getdate())
WHERE DATEDIFF(month, order_date_time, GetDate()) <= 3
The most important thing . . . These do different things. The first goes back three months. So, if today is April 15th, then it takes everything after Jan 15th.
The second looks at month boundaries. So, it counts all of the January the same way and takes all values since Jan 1.
Although you should use the version you need, the first version is much, much better. Basically, it can make use of indexes and partitions. The function call DATEDIFF() makes it hard (impossible?) for the optimizer to use indexes on order_date_time.
If you intend the second form, I would recommend rephrasing it as something like this:
WHERE order_date_time >= datefromparts(year(dateAdd(month, -3, getdate())), month(dateAdd(month, -3, getdate())), 1)
I know about Dateadd and datediff, but I cannot find any information how to use these functions on an actual date column rather than something like today's date with SQL Server.
Say I have the following Column
Dated
06/30/2015
07/31/2015
Now I want to add the following derived column that subtracts one month from every row in the Dated column.
Dated Subtracted
06/30/2015 05/31/2015
07/31/2015 06/30/2015
Thank you
The short answer: I suspect this is what you want:
dateadd(day, -datepart(day, Dated), Dated)
However, if you want "regular" subtract one month behavior in tandem with sticking to the end of month, having June 30 fall back to May 31 is slightly trickier. There's a discrepancy between the title or your question and the example where it appears you want the final day of month to stay anchored. It would be helpful for you to clarify this.
dateadd(month, -1, ...) doesn't handle that when the previous month has more days than the starting month although it works the other way around. If that's truly what you need I think this should handle it:
case
when datediff(month, Dated, dateadd(day, 1, Dated)) = 1
then dateadd(day, -datepart(day, Dated), Dated)
else dateadd(month, -1, Dated)
end
There's also a flavor of several date functions in that expression and a sense of how this date stuff can get complicated. The condition in the when looks to see if Dated is the last day of the month by checking that the following day is in a different calendar month. If so we extract the day of month and subtract that many days to jump back to the last day of the previous month. (Months start at one not zero. So for example, counting backward 17 days from the 17th lands in the month before.) Otherwise it uses regular dateadd(month, -1, ...) calculations to jump backward to the same day of month.
Of course if all your dates fall on the end of the month then this simple version will be adequate by itself because it always returns the last day of the previous month (regardless of where it falls in the starting month):
dateadd(day, -datepart(day, Dated), Dated) /* refer back to the top */
dateadd(day, -day(Dated), Dated) /* same thing */
And just for fun and practice with date expressions, another approach is that you could start on a known month with 31 days and calculate relative to that:
dateadd(month, datediff(month, '20151231', Dated) - 1, '20151231')
This finds the number of months between your date and a reference date. It works for all dates since it doesn't matter whether the difference is positive or negative. So then subtracting one from that difference and adding that many months to the reference point is the result you want.
People will come up with some pretty crazy stuff and I'm often amazed (for differing reasons) at some of the variations I see. chancrovsky's answer is a good example for closer examination:
dateadd(month, datediff(month, -1, Dated) - 1, -1)
It relies on the fact that date -1, when treated as implicitly converted to datetime, is the day before January 1, 1900, which does happen to be a month of 31 days as required. (Note that the - 1 in the middle is regular arithmetic and not a date value.) I think most people would advise you to be careful with that one as I'm not sure that it is guaranteed to be portable when Microsoft deprecates features in the future.
Why don't you just get the last day of the previous month? If this solve your problem, here's the sql server syntax, just replace the variable #yourDate with your column name.
DECLARE #yourDate DATE = '20160229'
select DATEADD(MONTH, DATEDIFF(MONTH, -1, #yourDate)-1, -1)
This also works if you're looking to find dates exactly 6 months behind.
Example:
DATEADD(DAY, DATEDIFF(DAY, -1, dates)-184, -31)
OK, so I have a load of records in a table and they have many different dates.
I want to retern only those records whose date falls on the last day of whatever quarter it's in.
I.e. I basically need the equivalent of a lastDayOfQuarter(date) function that calculates the date that is the last day in the quarter for the date passed to it.
e.g. lastDayOfQuarter(#16/05/2013#) = #30/06/2013#
My query might look like:
SELECT * FROM mytable
WHERE mytable.rdate = lastDayOfQuarter(mytable.rdate);
This query will be run over PDO so no VBA allowed. Native MS Access only.
I would also prefer to not use string manipulation as there is a difference between US and EU dates which might cause issues down the line.
I'm answering myself as, with the help of HansUp answering a previous question of mine for finding month-end records, I found out quite an easy way to acheive this:
WHERE DateValue(m.rdate) = DateSerial(Year(m.rdate), Month(m.rdate) + 1, 0)
AND Month(m.rdate) IN(3,6,9,12)
the "last day of the quarter" could be different for different users. You may be best to build a table of "lastdays" based on your business rules, then use that table in your query.
And here as short answer...Try
Select DateAdd(day, -1, dateadd(qq, DATEDIFF(qq, 0, 'year-month-day'), 0))
For today it should give you
2013-06-30 00:00:00.000
SO for your Table you should use :
SELECT * FROM mytable
WHERE mytable.rdate = DateAdd(day, -1, dateadd(qq, DATEDIFF(qq, 0, mytable.rdate), 0));
I'm trying to get the first and last day of the previous month. What I really need is a range for a BETWEEN clause, so I need the first second of the first day, and the last second of the last day.
This is the code I've been using:
set #startDate = DATEADD(mm, DATEDIFF(mm,0,DATEADD(mm, -1, getdate())), 0)
set #endDate = dateadd(ms,-3,DATEADD(mm, DATEDIFF(mm,0,getdate() ), 0))
However, for today, this is actually returning 4/1/2011 and 5/1/2011, which is not completely accurate. I want to get the last second of 4/30/2011 for the endDate.
I've been googling and I see many different ways to get the first/last day of a month. Even on SO itself, I see many different variations of this question with many different answers. I'd like to compile a list of all the methods to achieve this, and then determine which is the "best" (based on simplicity and efficiency)
(I should add that I'm using sql server 2000)
EDIT:
Re the enddate bug - this code is actually correct, the problem was just that #endDate was a smalldatetime. I changed it to a datetime and this is now working correctly
For dates I strongly recommend not using BETWEEN. This is highlighted by your need to remove 3ms from a date to get "the last moment of the previous day".
With continuous values (rather than discrete values), that can have varying degrees of accuracy, it is generally better to use >= AND <. For example...
WHERE myDateField >= '2012-04-01' AND myDateField < '2012-05-01'
By doing this you never need to even think about the accuracy of the myDateField data or data-type. It just works. Always.
With that in mind, your code is very close to what I would use...
SET #start = DATEADD(month, DATEDIFF(month, 0, getDate()) - 1, 0)
SET #end = DATEADD(month, DATEDIFF(month, 0, getDate()) , 0)
EDIT: as per the explanation from #Dems (please see the comments)
I think now my answer will be same as #Dems to we both are have same answers. :) #Dems Credit goes to you.
try this query it will get you the proper dates as per your need.
select DATEADD(mm, DATEDIFF(mm,0,DATEADD(mm, -1, GETDATE())), 0)
select DATEADD(mm, DATEDIFF(mm,0,GETDATE() ), 0)
and using this date you can directly use the >= and < as per the suggestion by #Dems below.