Week of the year in SQL Server - sql-server

I have one column in which I have to show the week of the another column [Sales Stage Date].
I used
DATEPART( wk, [Sales Stage Date])
But the issue is it takes week from Sunday to Saturday but I want it to take it as Monday to Sunday.
Example: 1st Aug 2021 should be in week 31 and not in week 32.

Sub a day off the date before you ask what week it's in
DATEPART( wk, DATEADD(day, -1, [Sales Stage Date]))
You'll need to handle the first day of the year directly with a CASE WHEN

Presumably the language your LOGIN is using (American) ENGLISH and thus the first day of the week is Sunday.
One method would be to change your language, but this feels excessive and would be specific to your LOGIN only.
Another is to explicitly set the DATEFIRST setting to 1 prior to the statement:
SET DATEFIRST 1;
SELECT DATEPART(WEEK, '20210802'),
DATEPART(WEEK, '20210101');
This, however, would be explicit to the connection where you changed the value of DATEFIRST so if you use this logic a lot you'd need to continuously force the value of DATEFIRST (which could break other code).
Depending on your business neeeds, however, you might be better off investing in creating a calendar table. Then you can JOIN to that table, and get the values you need agnostic of the LANGUAGE and date settings.

Related

Is there a convenient way to compare week-over-week data in SQL?

I have a table full of daily aggregate data, but I occasionally need to pull weekly aggregate data, and provide info on increases or decreases. For that reason, I was considering using T-SQL DATEPART functionality to get week-number and year info for dates.
For example, I can get the following info using today's date (9/11/2020):
#nowWeekNumber int = datepart(wk,#today), --yields 37
#nowYear int = datepart(year,#today), --yields 2020
Using that logic, I could then gather info on records where year is 2020 and weekNumber is 36, and then I could compare those numbers to get a weekly increase/decrease. (Or maybe I'd compare weeks 35 and 36 to ensure that I'm dealing w/ entire weeks, but you get the picture)
However, if the date is 2021-01-03, that's going to return a year of 2021, and a weekNumber of 2. If I subtract a week, I'm going to get year 2021 and weekNumber 1. That weekNumber is only going to contain January 1st and 2nd, because 12/27 thru 12/31 are considered year 2020 and weekNumber 53 (even though the calendar week is 12/27 thru 1/2).
In other words, I don't think I can use weekNumber to gather weekly data, even though that would be fairly convenient. I'm aware that I can use DATEADD functions to grab the start and end-date for consecutive weeks, and I can then gather aggregate data for records BETWEEN those dates, but is there a more-convenient way to do this?
Why don't you consider using dateDiff as key function? As...
select dateDiff(wk, 0, getDate())
Returns a single integer for the whole week (6297 for '20200911') and :
select dateAdd(wk, dateDiff(wk, 0, getDate()), 0),
dateAdd(dd, 6, dateAdd(wk, dateDiff(wk, 0, getDate()), 0))
or
select dateAdd(wk, 6297, 0),
dateAdd(dd, 6, dateAdd(wk, 6297, 0))
gives you the 1st and last day of that week.
You can use DATEPART but instead of wk you can use the iso week. Then you don't have the problem with a week being split in 2. To be sure also use SET DATEFIRST to define exactly on which day the week starts.
SET DATEFIRST 1; --use monday as first day of the week
SELECT datepart(iso_week,'2021-01-01');
SELECT datepart(iso_week,'2021-01-03');
SELECT datepart(iso_week,'2021-01-04');
The other option is to create your own calendar table and join that to your daily table.
EDIT: for a week start on sunday
SET DATEFIRST 7;
SELECT DATEPART(WEEK, DATEADD( DAY, 1-DATEPART(WEEKDAY,'2020-12-27'),'2020-12-27' ) )
SELECT DATEPART(WEEK, DATEADD( DAY, 1-DATEPART(WEEKDAY,'2020-12-28'),'2020-12-28' ) )
SELECT DATEPART(WEEK, DATEADD( DAY, 1-DATEPART(WEEKDAY,'2021-01-01'),'2021-01-01' ) )
SELECT DATEPART(WEEK, DATEADD( DAY, 1-DATEPART(WEEKDAY,'2021-01-02'),'2021-01-02' ) )

Produce data extracts using day field for the Friday before the weekend

Using TSQL on SQL Server...
I need to produce extracts that use a pay day column in a database that only holds the day number, for example 26 to produce extracts for the 26th day of the month with a twist if that pay day falls on a weekend then the data for that extract should be extracted the Friday before the weekend.
Has anybody attempted this and able to offer some ways of achieving this through TSQL?
Thanks
You have said in today's comment above that you are assuming the current month.
First turn your payday day number into a proper date:
select dateadd(month,((year(getdate())-1900)*12)+month(getdate())-1,payday-1)
as paydate
and then use a case statement against it:
case datename(weekday,paydate)
when 'Saturday' then dateadd(day,-1,paydate)
when 'Sunday' then dateadd(day,-2,paydate)
else paydate
end as paydateadjust
(Obviously these will need rewriting into a proper SQL statement. Date formula borrowed from Michael Valentine Jones' super useful SQL Server date function.)
I'm assuming you have the month and year available too, in which case you can construct a real date, and get the day of week from it as a 1-based number starting at Sunday. So, 6 equals Friday. This will produce 5 for today, as Thursday = 5
SELECT DATEPART(dw, DATEFROMPARTS(2018, 07, 26)) AS [DayOfWeek]
EDIT:
I'll make another assumption, this time that this is somehow possible, like it's always run for the current month. This is a bit dodgy as it all falls apart if it's run too early or too late, but at least it's achievable.
SELECT DATEPART(dw, DATEFROMPARTS(
DATEPART(YEAR, GETDATE()),
DATEPART(MONTH, GETDATE()),
26)) AS [DayOfWeekThisMonth]
EDIT 2:
OK, with the understanding we are working on this month, we can do this:
DECLARE #PayDayNumber INT = 29; -- Replace this with a SELECT to get your value
SELECT CASE(DATEPART(dw, DATEFROMPARTS(DATEPART(YEAR, GETDATE()), DATEPART(MONTH, GETDATE()), #PayDayNumber)))
WHEN 1 THEN #PayDayNumber - 2
WHEN 7 THEN #PayDayNumber - 1
ELSE #PayDayNumber
END AS [WeekendSafePayDay]
For this month (August 2018) the 29th will return 29th. You can change DATEPART(MONTH, GETDATE()) for 9 to test September, which will return 28 because 29th September is a Saturday, or change it to 7 to test July, which will return 27 because 29th July is a Sunday.

Return dates from last/this week depending on the current time and when "production" started

Sorry if the Title is confusing but it's hard to explain what I'm after in one phrase.
I'm currently producing a report based on the production for the week. I start off my CTE construction with the following to get the days Monday to Friday of the current week:
WITH
cte_Date AS
(
SELECT
CAST(DateTime AS date) AS Date
FROM
( VALUES
(GETDATE()
)
, (DATEADD(day,-1,GETDATE()))
, (DATEADD(day,-2,GETDATE()))
, (DATEADD(day,-3,GETDATE()))
, (DATEADD(day,-4,GETDATE()))
, (DATEADD(day,-5,GETDATE()))
, (DATEADD(day,-6,GETDATE())) ) AS LastSevenDays(DateTime)
WHERE
DATENAME(weekday, DateTime) = 'Monday'
UNION ALL
SELECT
DATEADD(day,1,Date)
FROM
cte_Date
WHERE
DATENAME(weekday,Date) <> 'Friday'
)
This is working fine. I have made the report available to users so they can run it anytime however sometimes nobody is available to run it last thing Friday. This means they don't get to see the full production for Friday and then the following week the CTE days change.
I'm trying to keep this a one-click affair so rather than introduce date parameters I proposed to the users that we adjust the query such that if they run the report before midday on "Monday" then it will show them last week's figures and they were happy with this (me and my big mouth). I put Monday in quotes because what we really mean of course is the first production day of the week.
My primary data table (which we'll call MyData) has a datetime field named DateTime (really!) that I can reference to determine the first day of production for the week.
One final caveat: Due to the layout of the report the users insisted that they always want to see the five days Monday to Friday, even if there is no production on a given day. (Consequently I do a LEFT JOIN from cte_Date to all other tables required.) So to be clear, right now as I'm typing this it's 11:45am local time on Tuesday and yesterday happened to be a public holiday here so running the report now should return Monday to Friday last week, but running it in 20 minutes time should return Monday to Friday this week.
Please help, my poor brain is getting twisted trying to figure it out.
There are a few different ways you can tackle this, but they all boil down to the same thing: you need a way of figuring out whether it's before or after 12pm on the first working day of the current week, then you need to get the Monday of the current "production week".
Let's just say, for simplicity's sake, you have some sort of table that contains public holidays (or non-production days). To find out whether it's the first day of the current production week, you basically just have to add the number of days in a row since the start of the week that have been public holidays.
Then you need to figure out whether it's before or after 12pm of that day.
If it's before you want last week's Monday-Friday. If it's after, you want this week's Monday-Friday.
Here's one way you might do this:
DECLARE #NonProductionDays TABLE (NPD DATE UNIQUE NOT NULL); -- Public holiday table.
INSERT #NonProductionDays (NPD) VALUES ('2017-09-25');
DECLARE #i INT = -- You don't need a variable for this, but just to keep things simple...
(
SELECT COUNT(*) -- Extract number of public holidays in a row this week before current date.
FROM #NonProductionDays AS N
WHERE DATEDIFF(WEEK, 0, N.NPD) = DATEDIFF(WEEK, 0, GETDATE())
AND N.NPD <= GETDATE()
AND (DATENAME(WEEKDAY, N.NPD) = 'Monday' OR EXISTS (SELECT 1 FROM #NonProductionDays AS N2 WHERE N2.NPD = DATEADD(DAY, -1, N.NPD)))
);
SELECT D = CAST(DATEADD(DAY, T.N, DATEADD(WEEK, DATEDIFF(HOUR, DATEADD(DAY, #i, '1900-01-01 12:00:00'), GETDATE()) / 24 / 7, '1900-01-01')) AS DATE)
FROM (VALUES (0), (1), (2), (3), (4)) AS T(N);
/*
Breaking this down:
X = DATEADD(DAY, #i, '1900-01-01 12:00:00')
-- Adds the number of NPD days this week to '1900-01-01 12:00:00'
-- So, for example, X would be '1900-01-02 12:00:00' this week
Y = DATEDIFF(HOUR, X, GETDATE()) / 24 / 7
-- The number of weeks between X and now, by taking the number of hours and dividing by 24 then by 7
-- The division is necessary to compare the hour.
-- So, for example, as of 11am on the September 26 2017, you'd get 6142.
-- As of 12pm on September 26 2017, you'd get 6143.
Z = DATEADD(WEEK, Y, '1900-01-01')
-- Just adds Y weeks to 1900-01-01, which was a Monday. This tells you the Monday of the current "production week".
-- So, for example, as of 11am on September 26 2017, you'd get '2017-09-18 00:00:00.000'.
-- As of 12pm on September 26 2017, you'd get '2017-09-25 00:00:00.000'.
Then we cast this as a date and add 0/1/2/3/4 days to it to get Monday, Tuesday, Wednesday, Thursday and Friday of the current "production week".
*/
I'm not sure I came up with the most efficient approach, but after a week of tossing it about in my brain this is what I came up with. I approached the problem from the opposite direction of that suggested by #ZLK.
My existing logic was already giving me the Monday of this week so in a subquery I looked for the first production record after Monday, stripped off the time with a DATEDIFF and made it midday with a DATEADD. I was then able to compare the current Date/Time with midday of the first production day to determine whether to reduce the date by one week.
I replaced this SELECT clause:
SELECT
CAST(DateTime AS date) AS Date
with this one:
SELECT -- Monday this week if it's after midday on the first production day otherwise Monday last week
DATEADD(week,IIF(GETDATE()>=DATEADD(hour,12,(
SELECT DATEDIFF(day,0,MIN(DateTime))
FROM MyData
WHERE CAST(MyData.DateTime AS date) >= CAST(LastSevenDays.DateTime AS date)
)),0,-1),CAST(LastSevenDays.DateTime AS date)) AS Date
To cater for the case where a new week has commenced but the operator runs the report before production starts I carefully arranged the boolean condition inside my IIF clause so that the empty result set from the subquery would mean the test returned FALSE and the operator would still see last week's figures.
(#ZLK, Thanks for your input - you did help my thinking a bit but I don't think your answer should be marked as correct. What I've come up with here is what I was originally requesting and didn't require the use of a static table.)

microsoft SQL - returning previous week's data

I have a script that I refresh every week to get the sales data of the last week with the duration starting from last week's Sunday and ending with last week's Saturday. For example if I am running the script in any day within the week from 09/18/16 to 09/24/16, I want to get the sales data spanning from 09.11.16 to 09.17.16.
What script/syntax can I use to get this data if I want to refresh in any day of the current week to get the previous week's data?
Appreciate your time,
Thanks!
You can try the following
declare #date date = getdate()
select dateadd(wk,-1,dateadd(dd, -(datepart(dw, #date)-1), #date)) as [Start],
dateadd(wk,-1,dateadd(dd, 7-(datepart(dw, #date)), #date)) as [End]
Here a working demo
Hope this will help you

Business Week Group in SQL (instead of calendar week)

My requirement is that I want to find business-week-ending (not the calender week) given a DATE column from the sales table in MSSQL.
Using different techniques I was able to find the [Calender] week-endings (and week-starting) dates corresponding to DATE in the table.
Since our business week ends on Wednesday [DOW 3 or 4 depending when the week started], I tried to deduct number of days from the week ending dates to pull it back to Wednesday. The idea did work pretty good with a flaw. Works fine as long as the Date in the table is greater than DOW 3 or 4. Any suggestion?
SELECT DateAdd(wk, DateDiff(wk, 0, Recons_Sales_Details.Recons_Date), 0) + 2
You need to look into SET DATEFIRST to do this:
SET DATEFIRST 4 --4 is Thursday week start
SQL Fiddle Demo

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