Calculate quarter for dates given an example end date and quarter number - sql

Question

I have an issue where I need to determine fiscal quarters, but won't always know the start/end dates for the quarters. They will, however, always be 3 months long. What I will know is the ending date of the current quarter, and what quarter and year that refers to. For example, I might be given:
Current Quarter: Q4
Current Year: 2021
Current Quarter End Date: 1/31/2021
How can I get the quarter for any other date? If any of those 3 values were to change, the query still needs to provide the quarter for any given date based on those 3 parameters.
I came up with the following, which puts the last 4 years into a temp table:
DECLARE #QuarterEnd DATE = '1/31/2022'
, #CurrentQuarter INT = 1
, #CurrentYear INT = 2022
, #Counter INT = 16
, #qs INT = 0
, #qe INT = 2
, #DateToTest DATE = '12/15/2021'
CREATE TABLE #Quarters (
StartDate DATE
, EndDate DATE
, Qtr INT
, Yr INT
)
WHILE #Counter <> 0
BEGIN
INSERT INTO #Quarters VALUES (
cast(DATEADD(MONTH, DATEDIFF(MONTH, 0, #QuarterEnd)-#qe , 0) as date)
, cast(DATEADD(MONTH, DATEDIFF(MONTH, -1, #QuarterEnd)-#qs, -1) as date)
, #CurrentQuarter
, #CurrentYear
)
SET #Counter = #Counter - 1
SET #qs = #qs + 3
SET #qe = #qe + 3
SET #CurrentQuarter = CASE WHEN #CurrentQuarter = 1 THEN 4 ELSE #CurrentQuarter - 1 END
SET #CurrentYear = CASE WHEN #CurrentQuarter = 4 THEN #CurrentYear - 1 ELSE #CurrentYear END
END
SELECT #DateToTest
, (SELECT CONCAT('Q', Qtr, ' ', Yr) FROM #Quarters WHERE #DateToTest BETWEEN StartDate and EndDate)
FROM #Quarters
However, this doesn't seem to be practical when I'm running queries that will return hundreds of thousands of records.
I suppose I can throw that into a function and call it with:
SELECT MyQuarter = dbo.MyQuarterFunction(#QuarterEnd, #CurrentQuarter, #CurrentYear, #DateToTest)
There has to be a more efficient way to do this. Any suggestions?

Answer 1

Just create a permanent table called Quarters.
CREATE TABLE dbo.Quarters
(
StartDate date,
QuarterNumber tinyint,
FiscalYear int,
NextQuarterStartDate AS (DATEADD(MONTH, 3, StartDate))
);
INSERT dbo.Quarters(StartDate, QuarterNumber, FiscalYear)
VALUES('20200201',1,2020),
('20200501',2,2020),
('20200801',3,2020),
('20201101',4,2020),
('20210201',1,2021),
('20210501',2,2021),
('20210801',3,2021),
('20211101',4,2021),
('20220201',1,2022),
('20220501',2,2022),
('20220801',3,2022),
('20221101',4,2022);
Now any time you are given a date (like GETDATE()) you can find the other information easily:
DECLARE #date date = GETDATE();
SELECT * FROM dbo.Quarters
WHERE #date >= StartDate
AND #date < NextQuarterStartDate;
Example db<>fiddle
If you need to support multiple fiscal calendars simultaneously, just add a column (like CalendarID or CompanyID or CustomerID).
And really, you don't even need a calendar or quarters table for this. You already have a table of clients, right? Just add a column to store what month their fiscal year starts. That's really all you need.
CREATE TABLE dbo.Clients
(
ClientID int NOT NULL CONSTRAINT PK_Clients PRIMARY KEY,
Name nvarchar(200) NOT NULL CONSTRAINT UQ_ClientName UNIQUE,
FiscalYearStart tinyint NOT NULL CONSTRAINT CK_ValidMonth
CHECK (FiscalYearStart BETWEEN 1 AND 12)
);
Now let's insert a few rows with some clients with different fiscal years:
INSERT dbo.Clients(ClientID, Name, FiscalYearStart)
VALUES(1, N'ClientFeb', 2), -- fiscal year starts in February
(2, N'ClientMay', 5), -- fiscal year starts in May
(3, N'ClientNormal', 1); -- fiscal year matches calendar
Now, yes, we need a function, but let's not do any while loops or counters or #temp tables.
CREATE FUNCTION dbo.GetLast16Quarters
(
#DateToTest date,
#ClientID int
)
RETURNS TABLE WITH SCHEMABINDING AS
RETURN
(
WITH n(n) AS
(
SELECT n = 1 UNION ALL
SELECT n + 1 FROM n WHERE n < 20
),
Last20Quarters(QuarterStart, FiscalYearStart) AS
(
SELECT QuarterStart = DATEADD(QUARTER, 1-n,
DATEFROMPARTS(YEAR(#DateToTest)+1, FiscalYearStart, 1)),
FiscalYearStart
FROM dbo.Clients CROSS JOIN n WHERE ClientID = #ClientID
),
Last16Quarters AS
(
SELECT TOP (16) QuarterStart,
y = YEAR(DATEADD(MONTH, 1-FiscalYearStart, QuarterStart))
FROM Last20Quarters WHERE QuarterStart < #DateToTest
ORDER BY QuarterStart DESC
)
SELECT QuarterStart,
QuarterEnd = EOMONTH(QuarterStart, 2),
FiscalYear = y,
QuarterNumber = ROW_NUMBER() OVER
(PARTITION BY y ORDER BY QuarterStart)
FROM Last16Quarters);
Then to call it:
DECLARE #DateToTest date = '20211215';
SELECT * FROM dbo.GetLast16Quarters(#DateToTest, 1);
Output:
QuarterStart
QuarterEnd
FiscalYear
QuarterNumber
2018-02-01
2018-04-30
2018
1
2018-05-01
2018-07-31
2018
2
2018-08-01
2018-10-31
2018
3
2018-11-01
2019-01-31
2018
4
2019-02-01
2019-04-30
2019
1
2019-05-01
2019-07-31
2019
2
2019-08-01
2019-10-31
2019
3
2019-11-01
2020-01-31
2019
4
2020-02-01
2020-04-30
2020
1
2020-05-01
2020-07-31
2020
2
2020-08-01
2020-10-31
2020
3
2020-11-01
2021-01-31
2020
4
2021-02-01
2021-04-30
2021
1
2021-05-01
2021-07-31
2021
2
2021-08-01
2021-10-31
2021
3
2021-11-01
2022-01-31
2021
4
Example db<>fiddle

Answer 2

Assuming that you have two input variables:
declare #quarter_end date = '2021-01-31';
declare #current_quarter int = 4;
You can calculate the first month of financial year:
declare #first_month_of_fy int = (month(#quarter_end) - #current_quarter * 3 + 12) % 12 + 1;
-- 2 i.e. February
And use that value to calculate the quarter and year for any date using some math:
select *
from (values
('2020-12-15'),
('2021-01-15'),
('2021-12-15'),
('2022-01-15')
) as t(testdate)
cross apply (select
(month(testdate) - #first_month_of_fy + 12) % 12 + 1
) as ca1(month_of_fy)
cross apply (select
(month_of_fy - 1) / 3 + 1,
year(dateadd(month, 12 - month_of_fy, dateadd(day, - day(testdate) + 1, testdate)))
) as ca2(fy_quarter, fy_year)
DB<>Fiddle

Answer 3

I ended up creating a function to handle this. Since I'm given the last day of the quarter, which quarter it is, and which year it is, I can determine the start and end date of that fiscal year. Since a quarter is always 3 months, I can also determine which months fall into which quarter.
The first 4 variables, #qa, #qb, #qc, #qd hold a comma separated list of the months within each quarter (#qa is current quarter, #qb is current quarter -1, #qc is current quarter -2, and #qd is current quarter -3)
The second 2 variables determine the first day and last day of the fiscal calendar
To get the quarter & year, I first get the month from the supplied date (#Date) and see if it's in #qa, #qb, #qc or #qd. That tells me the fiscal quarter.
Finally, I compare the given date to the start and end date of the current fiscal year, and to the 6 years prior (going back 6 years is enough for what I need)
CREATE FUNCTION [dbo].[FunctionNameHere]
(
#Date DATE
, #QuarterEnd DATE
, #CurrentQuarter INT
, #CurrentYear INT
)
RETURNS VARCHAR(7)
AS
BEGIN
DECLARE #qa VARCHAR(8) = (concat(datepart(m, dateadd(m, 0, #QuarterEnd)),',', datepart(m, dateadd(m, -1, #QuarterEnd)),',', datepart(m, dateadd(m, -2, #QuarterEnd))))
DECLARE #qb VARCHAR(8) = (concat(datepart(m, dateadd(m, -3, #QuarterEnd)),',', datepart(m, dateadd(m, -4, #QuarterEnd)),',', datepart(m, dateadd(m, -5, #QuarterEnd))))
DECLARE #qc VARCHAR(8) = (concat(datepart(m, dateadd(m, -6, #QuarterEnd)),',', datepart(m, dateadd(m, -7, #QuarterEnd)),',', datepart(m, dateadd(m, -8, #QuarterEnd))))
DECLARE #qd VARCHAR(8) = (concat(datepart(m, dateadd(m, -9, #QuarterEnd)),',', datepart(m, dateadd(m, -10, #QuarterEnd)),',', datepart(m, dateadd(m, -11, #QuarterEnd))))
DECLARE #YearStart DATE = DATEADD(d, 1, DATEADD(q, -#CurrentQuarter, #QuarterEnd))
DECLARE #YearEnd DATE = DATEADD(q, 4-#CurrentQuarter, #QuarterEnd)
DECLARE #Qtr VARCHAR(8) = CONCAT('Q', CASE WHEN DATEPART(m, #Date) IN (SELECT value FROM string_split(#qa, ',')) THEN #CurrentQuarter
WHEN DATEPART(m, #Date) IN (SELECT value FROM string_split(#qb, ',')) THEN CASE WHEN #CurrentQuarter = 1 THEN 4
WHEN #CurrentQuarter = 2 THEN 1
WHEN #CurrentQuarter = 3 THEN 2
WHEN #CurrentQuarter = 4 THEN 3 END
WHEN DATEPART(m, #Date) IN (SELECT value FROM string_split(#qc, ',')) THEN CASE WHEN #CurrentQuarter = 1 THEN 3
WHEN #CurrentQuarter = 2 THEN 4
WHEN #CurrentQuarter = 3 THEN 1
WHEN #CurrentQuarter = 4 THEN 2 END
WHEN DATEPART(m, #Date) IN (SELECT value FROM string_split(#qd, ',')) THEN CASE WHEN #CurrentQuarter = 1 THEN 2
WHEN #CurrentQuarter = 2 THEN 3
WHEN #CurrentQuarter = 3 THEN 4
WHEN #CurrentQuarter = 4 THEN 1 END
END,
' ',
CASE WHEN #Date BETWEEN #YearStart AND #YearEnd THEN #CurrentYear
WHEN #Date BETWEEN dateadd(Year, -1, #YearStart) AND dateadd(Year, -1, #YearEnd) THEN #CurrentYear - 1
WHEN #Date BETWEEN dateadd(Year, -2, #YearStart) AND dateadd(Year, -2, #YearEnd) THEN #CurrentYear - 2
WHEN #Date BETWEEN dateadd(Year, -3, #YearStart) AND dateadd(Year, -3, #YearEnd) THEN #CurrentYear - 3
WHEN #Date BETWEEN dateadd(Year, -4, #YearStart) AND dateadd(Year, -4, #YearEnd) THEN #CurrentYear - 4
WHEN #Date BETWEEN dateadd(Year, -5, #YearStart) AND dateadd(Year, -5, #YearEnd) THEN #CurrentYear - 5
WHEN #Date BETWEEN dateadd(Year, -6, #YearStart) AND dateadd(Year, -6, #YearEnd) THEN #CurrentYear - 6
ELSE 9999 END)
return #Qtr
END