How To Select Records in a Status Between Timestamps? T-SQL - sql

Question

I have a T-SQL Quotes table and need to be able to count how many quotes were in an open status during past months.
The dates I have to work with are an 'Add_Date' timestamp and an 'Update_Date' timestamp. Once a quote is put into a 'Closed_Status' of '1' it can no longer be updated. Therefore, the 'Update_Date' effectively becomes the Closed_Status timestamp.
I'm stuck because I can't figure out how to select all open quotes that were open in a particular month.
Here's a few example records:
Quote_No Add_Date Update_Date Open_Status Closed_Status
001 01-01-2016 NULL 1 0
002 01-01-2016 3-1-2016 0 1
003 01-01-2016 4-1-2016 0 1
The desired result would be:
Year Month Open_Quote_Count
2016 01 3
2016 02 3
2016 03 2
2016 04 1
I've hit a mental wall on this one, I've tried to do some case when filtering but I just can't seem to figure this puzzle out. Ideally I wouldn't be hard-coding in dates because this spans years and I don't want to maintain this once written.
Thank you in advance for your help.

Answer 1

You are doing this by month. So, three options come to mind:
A list of all months using left join.
A recursive CTE.
A number table.
Let me show the last:
with n as (
select row_number() over (order by (select null)) - 1 as n
from master..spt_values
)
select format(dateadd(month, n.n, q.add_date), 'yyyy-MM') as yyyymm,
count(*) as Open_Quote_Count
from quotes q join
n
on (closed_status = 1 and dateadd(month, n.n, q.add_date) <= q.update_date) or
(closed_status = 0 and dateadd(month, n.n, q.add_date) <= getdate())
group by format(dateadd(month, n.n, q.add_date), 'yyyy-MM')
order by yyyymm;
This does assume that each month has at least one open record. That seems reasonable for this purpose.

Answer 2

You can use datepart to extract parts of a date, so something like:
select datepart(year, add_date) as 'year',
datepart(month, date_date) as 'month',
count(1)
from theTable
where open_status = 1
group by datepart(year, add_date), datepart(month, date_date)
Note: this counts for the starting month and primarily to show the use of datepart.

Answer 3

Updated as misunderstood the initial request.
Consider following test data:
DECLARE #test TABLE
(
Quote_No VARCHAR(3),
Add_Date DATE,
Update_Date DATE,
Open_Status INT,
Closed_Status INT
)
INSERT INTO #test (Quote_No, Add_Date, Update_Date, Open_Status, Closed_Status)
VALUES ('001', '20160101', NULL, 1, 0)
, ('002', '20160101', '20160301', 0, 1)
, ('003', '20160101', '20160401', 0, 1)
Here is a recursive solution, that doesn't rely on system tables BUT also performs poorer. As we are talking about months and year combinations, the number of recursions will not get overhand.
;WITH YearMonths AS
(
SELECT YEAR(MIN(Add_Date)) AS [Year]
, MONTH(MIN(Add_Date)) AS [Month]
, MIN(Add_Date) AS YMDate
FROM #test
UNION ALL
SELECT YEAR(DATEADD(MONTH,1,YMDate))
, MONTH(DATEADD(MONTH,1,YMDate))
, DATEADD(MONTH,1,YMDate)
FROM YearMonths
WHERE YMDate <= SYSDATETIME()
)
SELECT [Year]
, [Month]
, COUNT(*) AS Open_Quote_Count
FROM YearMonths ym
INNER JOIN #test t
ON (
[Year] * 100 + [Month] <= CAST(FORMAT(t.Update_Date, 'yyyyMM') AS INT)
AND t.Closed_Status = 1
)
OR (
[Year] * 100 + [Month] <= CAST(FORMAT(SYSDATETIME(), 'yyyyMM') AS INT)
AND t.Closed_Status = 0
)
GROUP BY [Year], [Month]
ORDER BY [Year], [Month]
Statement is longer, also more readable and lists all year/month combinations to date.
Take a look at Date and Time Data Types and Functions for SQL-Server 2008+
and Recursive Queries Using Common Table Expressions