Display data for all date ranges including missing dates - sql

Question

I'm having a issue with dates. I have a table with given from and to dates for an employee. For an evaluation, I'd like to display each date of the month with corresponding values from the second sql table.
SQL Table:
EmpNr | datefrom | dateto | hours
0815 | 01.01.2019 | 03.01.2019 | 15
0815 | 05.01.2019 | 15.01.2019 | 15
0815 | 20.01.2019 | 31.12.9999 | 40
The given employee (0815) worked during 01.01.-15.01. 15 hours, and during 20.01.-31.01. 40 hours
I'd like to have the following result:
0815 | 01.01.2019 | 15
0815 | 02.01.2019 | 15
0815 | 03.01.2019 | 15
0815 | 04.01.2019 | NULL
0815 | 05.01.2019 | 15
...
0815 | 15.01.2019 | 15
0815 | 16.01.2019 | NULL
0815 | 17.01.2019 | NULL
0815 | 18.01.2019 | NULL
0815 | 19.01.2019 | NULL
0815 | 20.01.2019 | 40
0815 | 21.01.2019 | 40
...
0815 | 31.01.2019 | 40
as for the dates, we have:
declare #year int = 2019, #month int = 1;
WITH numbers
as
(
Select 1 as value
UNion ALL
Select value + 1 from numbers
where value + 1 <= Day(EOMONTH(datefromparts(#year,#month,1)))
)
SELECT b.empnr, b.hours, datefromparts(#year,#month,numbers.value) Datum FROM numbers left outer join
emptbl b on b.empnr = '0815' and (datefromparts(#year,#month,numbers.value) >= b.datefrom and datefromparts(#year,#month,numbers.value) <= case b.dateto )
which is working quite well, yet I have the odd issue, that this code is only shoes the dates between 01.01.2019 and 03.01.2019
thank you very much in advance!

Answer 1

Did you check, if datefrom and dateto is in correct range?
Minimum value of DateTime field is 1753-01-01 and maximum value is 9999-12-31.
Look at your source table to check initial values.

Answer 2

The recursive CTE needs to begin with MIN(datefrom) and MAX(dateto):
DECLARE #t TABLE (empnr INT, datefrom DATE, dateto DATE, hours INT);
INSERT INTO #t VALUES
(815, '2019-01-01', '2019-01-03', 15),
(815, '2019-01-05', '2019-01-15', 15),
(815, '2019-01-20', '9999-01-01', 40),
-- another employee
(999, '2018-01-01', '2018-01-31', 15),
(999, '2018-03-01', '2018-03-31', 15),
(999, '2018-12-01', '9999-01-01', 40);
WITH rcte AS (
SELECT empnr
, MIN(datefrom) AS refdate
, ISNULL(NULLIF(MAX(dateto), '9999-01-01'), CURRENT_TIMESTAMP) AS maxdate -- clamp year 9999 to today
FROM #t
GROUP BY empnr
UNION ALL
SELECT empnr
, DATEADD(DAY, 1, refdate)
, maxdate
FROM rcte
WHERE refdate < maxdate
)
SELECT rcte.empnr
, rcte.refdate
, t.hours
FROM rcte
LEFT JOIN #t AS t ON rcte.empnr = t.empnr AND rcte.refdate BETWEEN t.datefrom AND t.dateto
ORDER BY rcte.empnr, rcte.refdate
OPTION (MAXRECURSION 1000) -- approx 3 years
Demo on db<>fiddle

Answer 3

It could be in your select, try:
SELECT b.empnr, b.hours, datefromparts(#year,#month,numbers.value) Datum
FROM numbers
LEFT OUTER JOIN emptbl b ON b.empnr = '0815' AND
datefromparts(#year,#month,numbers.value) BETWEEN b.datefrom AND b.dateto

Answer 4

Your CTE produces only 31 number and therefore it is showing only January dates.
declare #year int = 2019, #month int = 1;
WITH numbers
as
(
Select 1 as value
UNion ALL
Select value + 1 from numbers
where value + 1 <= Day(EOMONTH(datefromparts(#year,#month,1)))
)
SELECT *
FROM numbers
https://dbfiddle.uk/?rdbms=sqlserver_2017&fiddle=a24e58ef4ce522d3ec914f90907a0a9e
You can try below code,
with t0 (i) as (select 0 union all select 0 union all select 0),
t1 (i) as (select a.i from t0 a ,t0 b ),
t2 (i) as (select a.i from t1 a ,t1 b ),
t3 (srno) as (select row_number()over(order by a.i) from t2 a ,t2 b ),
tbldt(dt) as (select dateadd(day,t3.srno-1,'01/01/2019') from t3)
select tbldt.dt
from tbldt
where tbldt.dt <= b.dateto -- put your condition here
https://dbfiddle.uk/?rdbms=sqlserver_2017&fiddle=b16469908b323b8d1b98d77dd09bab3d