Oracle SQL Show all month of a year, with or without value ORA-01841 - sql

Question

I have a problem with which I despair, I have data distributed over days, and would like to display this for the entire year in months and once in weeks.
My problem with the months that I get in the select my data displayed (for January, September) but I want that all months for a selected year are displayed, even if they are empty. For this I have made myself a "WITH" (copied) and now try to join this, but get an ORA-01841 error.
And how do I implement the whole construct to display only the weeks.
WITH MONAT_ZAEHLER (MZ) AS
(
SELECT
TO_CHAR(ADD_MONTHS(TO_DATE('01.2022','MM.YYYY'),LEVEL -1),'Month', 'NLS_DATE_LANGUAGE = GERMAN') AS GRD_ROW_ID
FROM
DUAL
CONNECT BY LEVEL <= 12
)
SELECT
TO_CHAR(GEN_DATUM,'Month', 'NLS_DATE_LANGUAGE = GERMAN') AS GRD_ROW_ID
, COUNT( DISTINCT CASE
WHEN LP_BELEGUNG.ART = 1 THEN LP_BELEGUNG.LP_BELEGUNG_ID
ELSE NULL
END ) AS "1"
, COUNT( DISTINCT CASE
WHEN LP_BELEGUNG.ART = 2 THEN LP_BELEGUNG.LP_BELEGUNG_ID
ELSE NULL
END ) AS "2"
, COUNT( DISTINCT CASE
WHEN LP_BELEGUNG.ART = 3 THEN LP_BELEGUNG.LP_BELEGUNG_ID
ELSE NULL
END ) AS "3"
, COUNT( DISTINCT CASE
WHEN LP_BELEGUNG.ART = 99 THEN LP_BELEGUNG.LP_BELEGUNG_ID
ELSE NULL
END ) AS "99"
FROM
LP_BELEGUNG
FULL OUTER JOIN MONAT_ZAEHLER ON TRUNC(LP_BELEGUNG.GEN_DATUM, 'Month') = MONAT_ZAEHLER.MZ
WHERE
TO_CHAR(GEN_DATUM, 'YYYY') = '2022'
GROUP BY
TO_CHAR(GEN_DATUM,'Month', 'NLS_DATE_LANGUAGE = GERMAN')

Answer 1

The error is because you're converting the month to a name string in the CTE, then trying to convert it again for the GRD_ROW_ID alias.
The solution is basically the same as your previous question, but now you want the CTE to have one row per month - which you are doing, but you should leave it as a date type in the CTE, not convert it to a string there:
with cte (dt) as (
select add_months(date '2022-01-01', level - 1)
from dual
connect by level <= 12
)
... then convert that actual date value to a string:
SELECT
TO_CHAR(cte.dt, 'Month', 'NLS_DATE_LANGUAGE = GERMAN') AS GRD_ROW_ID
...
... and outer join to your actual table as before, using a date range:
FROM
cte
LEFT JOIN
LP_BELEGUNG
ON
LP_BELEGUNG.GEN_DATUM >= cte.dt AND LP_BELEGUNG.GEN_DATUM < add_months(cte.dt, 1)
GROUP BY
cte.dt
ORDER BY
cte.dt
... this time looking for values where the the GEN_DATUM is greater than or equal to cte.dt value (again, as before), which is midnight on the first day of the first day of the month; and less than add_months(cte.dt, 1), which is midnight on the first day of the first day of the following month. So for January, that will be >= 2022-01-01 00:00:00 and < 2022-02-01 00:00:00, which is all possible dates and times during that month.
GRD_ROW_ID
ANZAHL_ART_1
ANZAHL_ART_2
ANZAHL_ART_3
ANZAHL_ART_4
Januar
0
0
0
0
Februar
0
0
0
0
März
0
0
0
0
April
0
0
0
0
Mai
0
0
0
0
Juni
0
0
0
0
Juli
0
0
0
0
August
0
0
0
0
September
1
1
1
7
Oktober
0
0
0
0
November
0
0
0
0
Dezember
0
0
0
0
fiddle
To get a row for every week of the year you would do something similar again, but in blocks of 7 days:
with cte (dt) as (
select date '2022-01-01' + 7 * (level - 1)
from dual
connect by level <= 53
)
SELECT
TO_CHAR(cte.dt, 'YYYY-WW') AS GRD_ROW_ID
...
FROM
cte
LEFT JOIN
LP_BELEGUNG
ON
LP_BELEGUNG.GEN_DATUM >= cte.dt AND LP_BELEGUNG.GEN_DATUM < cte.dt + 7
AND LP_BELEGUNG.GEN_DATUM < add_months(trunc(cte.dt, 'YYYY'), 12)
GROUP BY
cte.dt
ORDER BY
cte.dt
which has an extra check in the join to stop it including data from week 53 which is actually in the following year - which I'm guessing you woudl want to do.
fiddle