SQL - Count month difference in non-consecutive date period - sql

I am trying to extract how many months of membership a member gets up to date. As the picture shows, this member got four years of subscription since 2018. However, she stopped the subscription for a year ending in 2019. And then, restart the membership in 2020 again.
Each membership lasts for 12 months. if we look at the last membership starting from 2022-05-08, it will end up on 2023-05-08. However, I only want to get the total month count up to date(getdate - 2022-09-14).
Please advise how I could approach this matter. Thanks!
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Assuming you were planning to apply sum(monthcount), you could wrap the monthcount within a CASE statement to checks if the vip_end is greater than today's date:
sum(case when vip_end > getdate() then ... else monthcount end)
What you do within that ... depends on whether you wanted to just count the different number of months within the date range (e.g. 31st Jan -> 01st Feb is counted as a whole month because it just considers Jan -> Feb):
datediff(month, datecreated, getdate())
or perhaps calculate the number of months based on the average days in a month:
datediff(day, datecreated, getdate())*12.0/365.25
or maybe something else... it really depends on what level of detail you want to achieve.

Related

SQL - check if an order date occurs after the second Saturday in July

I am querying against a table of 4 yrs of order transactions (pk = order number) and I'm looking to tag each record with particular date flags based on the order date - e.g., calendar year, calendar month, fiscal year, etc. There are date attributes that are specific to our business (e.g., not easily solved by a datepart function) that I'm having trouble with.
I was able to add "School Year" (for us that runs Aug 1 - July 31) using a case statement:
case
when datepart(month, oline.order_date_ready) between 8 and 12 then datepart(year, oline.order_date_ready)
else (datepart(year, oline.order_date_ready)-1)
end as school_yr
So for 1/19/2017, the above would return "2016", because to us the 2016 school year runs from Aug 1 2016 to July 31 2017.
But now I'm having trouble repeating the same kind of case statement for something called "Rollover Year". All of our order history tables are reset/"rolled over" on the 2nd Saturday in July every calendar year, so for example the most recent rollover date was Saturday July 9th 2016. Click to view - rollover year date ranges
My above case statement doesn't apply anymore because I can't just add "datepart(month, oline.order_date_ready) = 7" - I don't need the whole month of July, I just need all the orders occurring after the 2nd Saturday in that July. So in this example, I need everything occurring from Sat July 9 2016 to today to be flagged as rollover_date = 2016.
Is there a flexible way to do this without hard coding previous/future rollover dates into another table? That's the only way I can think to solve it currently, but I'm sure there must be a better way.
Thanks!
If you ask for the day-of-the-week of July 1st, then from there it's simple arithmetic, right? This query gives results matching your image:
SELECT y,
CONCAT(y, '-07-01')::timestamp +
CONCAT(6 - EXTRACT(DOW FROM CONCAT(y, '-07-01')::timestamp) + 7, ' days')::interval
FROM generate_series(2013, 2020) s(y)
ORDER BY y DESC
;
So given any date d from year y, if it comes before the 2nd Saturday of July, give it fiscal year y - 1. Otherwise give it fiscal year (school year?) y.

Oracle Week Number from a Date

I am brand new to Oracle. I have figured out most of what I need but one field is driving me absolutely crazy. Seems like it should be simple but I think my brain is fried and I just can't get my head around it. I am trying to produce a Sales report. I am doing all kinds of crazy things based on the Invoice Date. The last thing I need to do is to be able to create a Week Number so I can report on weekly sales year vs year. For purposes of this report my fiscal year starts exactly on December 1 (regardless of day of week it falls on) every year. For example, Dec 1-7 will be week 1, etc. I can get the week number using various functions but all of them are based on either calendar year or ISO weeks. How can I easily generate a field that will give me the number of the week since December 1? Thanks so much for your help.
Forget about the default week number formats as that won't work for this specific requirement. I'd probably subtract the previous 1 December from invoice date and divide that by 7. Round down, add 1 and you should be fine.
select floor(
(
trunc(invoiceDate) -
case
-- if December is current month, than use 1st of this month
when to_char(invoiceDate, 'MM') = '12' then trunc(invoiceDate, 'MM')
-- else, use 1st December of previous year
else add_months(trunc(invoiceDate, 'YYYY'), -1)
end
) / 7
) + 1
from dual;

Get the EOM and MOM of any month in SQL Server 2005

I've periods of time every 15 days, MOM and EOM.
What I need to check is if a date value on a date field is prior to the current period minus 1.
For example, if today is 12/29, the period is 12/31, and i need to check
if prior < 12/15
How can i get the EOM (End Of Month, i mean, the last day of the month) and the MOM (Middle of month, it's like every 15th of month) with GETDATE() function without doing a DATEADD with -15 days (because in feb will be fail, and i don't care the month)
Any help or work around will be preciated.
Thanks
If you need the value 15 then put it in your code.
If that is against your company's policies then challenge the person that made that policy. Writing 5 lines of code to replace two characters is not a good coding...
If writing the 5 lines made your application much more flexible then maybe I could understand, but you are still "hard coding" 15 into your comparisons.
Thinking in a work around, what I did it was this:
If actual day < 15 then get the month actual, convert to the first day of the month (01) and minus 1 day. I get the last day of the prior month. (EOM - 1 period)
If actual day > 15, then the prior period (MOM - 1 period) is: 15 of actual month.
It's a query with if structure.
If someone has a better answer, please answer it and I'll be accept it.
Thanks :)

Access query (SQL) to return records sorted (grouped by) WEEKS

Greetings SQL gurus,
I don't know if you can help me, but I will try. I have several large databases grouped by year (each year in a different database). I want to be able to compare values from a particular week from one year to the next. For example, "show me week 17 of 2008 vs. week 17 of 2002."
I have the following definition of weeks that ideally I would use:
Only 52 weeks each year and 7 days a week (that only takes 364 days),
The first day of the first week starts from January 2nd - which means we do not use January 1st data, and
In leap year, the first day of the first week ALSO starts from the January 2nd plus we skip Feb. 29.
Any ideas?
Thanks in advance.
Best to avoid creating a table because then you have to update and maintain it to get your queries to work.
DatePart('ww',[myDate]) will give you the week number. You may run into some issues though deciding which week belongs to which year - for example if Jan 1 2003 is on Wednesday does the week belong as week 52 in 2002 or week 1 in 2003? Your accounting department will have a day of the week that is your end of week (usually Sat). I usually just pick the year that has the most days in it. DatePart will always count the first week as 1 and in the case of the example above the last week as 53. You may not care that much either way. You can create queries for each year
SELECT DatePart('ww',[myDate]) as WeekNumber,myYearTable.* as WeekNumber
FROM myYearTable
and then join the queries to get your data. You'll loose a couple days at the end of the year if one table has 52 weeks and one has 53 (most will show as 53). Or you can do it by your weekending day - this always gives you Saturday which would push a late week into the following year.
(7-Weekday([myDate]))+[myDate]
then
DatePart('ww',(7-Weekday([myDate]))+[myDate])
Hope that helps
To get the week number
'to get the week number in the year
select datepart( week, datefield)
'to get the week number in the month
select (datepart(dd,datefield) -1 ) / 7 + 1
You don't need to complicate things thinking about leap years, etc. Just compare weeks mon to sun
SInce you havea a specifc defintion of when the week starts that is differnt that the standard used by the db, I think a weeks table is the solution to your problem. For each year create a table that defines the dates contained in each week and the week number. Then by joining to that table as well as the relevant other tables, you can ask for just the data for week 17.
Table structure
Date Week
20090102 1
20090103 1
etc.
I needed to create a query that shows BOTH year AND week numbers, like 2014-52. The year shows correct when you use the Datepart() formula to convert week 53 to week 52 in the previous year, but shows the wrong year for the week that was week 1 previously that should be week 52 now. It show that week as 2015-52 instead of 2014-52.
Furthermore, it sorts the data wrong if you only use only the week number, eg:
2014-1,2014-11,2014-2
To overcome this I created the following query to insert a 0 and also to check for days in week 1 that should still fall under week 52.
ActualWeek: IIf(DatePart("ww",[SomeDate],1,3)=52 And DatePart("ww",[SomeDate])=1, DatePart("yyyy",[SomeDate],1,3)-1,DatePart("yyyy",[SomeDate],1,3)) & "-" & IIf(DatePart("ww",[SomeDate],1,3)<10,"0" & DatePart("ww",[SomeDate],1,3),DatePart("ww",[SomeDate],1,3))

T-SQL absence by month from start date end date

I have an interesting query to do and am trying to find the best way to do it. Basically I have an absence table in our personnel database this records the staff id and then a start date and end date for the absence. End date being null if not yet entered (not returned). I cannot change the design.
They would like a report by month on number of absences (12 month trend). With staff being off over the month change it obviously may be difficult to calculate.
e.g. Staff off 25/11/08 to 05/12/08 (dd/MM/yy) I would want the days in November to go into the November count and the ones in December in the December count.
I am currently thinking in order to count the number of days I need to separate the start and end date into a record for each day of the absence, assigning it to the month it is in. then group the data for reporting. As for the ones without an end date I would assume null is the current date as they are presently still absent.
What would be the best way to do this?
Any better ways?
Edit: This is SQL 2000 server currently. Hoping for an upgrade soon.
I have had a similar issue where there has been a table of start/end dates designed for data storage but not for reporting.
I sought out the "fastest executing" solution and found that it was to create a 2nd table with the monthly values in there. I populated it with the months from Jan 2000 to Jan 2070. I'm expecting it will suffice or that I get a large pay cheque in 2070 to come and update it...
DECLARE TABLE months (start DATETIME)
-- Populate with all month start dates that may ever be needed
-- And I would recommend indexing / primary keying by start
SELECT
months.start,
data.id,
SUM(CASE WHEN data.start < months.start
THEN DATEDIFF(DAY, months.start, data.end)
ELSE DATEDIFF(DAY, data.start, DATEADD(month, 1, months.start))
END) AS days
FROM
data
INNER JOIN
months
ON data.start < DATEADD(month, 1, months.start)
AND data.end > months.start
GROUP BY
months.start,
data.id
That join can be quite slow for various reasons, I'll search out another answer to another question to show why and how to optimise the join.
EDIT:
Here is another answer relating to overlapping date ranges and how to speed up the joins...
Query max number of simultaneous events