As stated in the other thread, download and install the following function in your DB

CREATE_FUNCTION_dbo_DelimitedSplit8K_LEAD.sql

Then use it as follows

WITH cteTwoWords AS (
  SELECT TwoWords =...

Did you download and install dbo.DelimitedSplit8K on your SQL instance?

If you are using an earlier version of SQL, then I suggest that you read Tally OH! An Improved SQL 8K “CSV Splitter” Function by Jeff Moden. ...

As ratbak indicated, you have posted in a SQL 2022 forum.  As such, my proposed solution uses functionality that is available in SQL 2022.

If you are using SQL 2012 to...

We cannot dump an image of your data in SSMS to test any code.

So, I made up some dummy data for myself.

The following code appears to do what you are...

If I run your code against your sample data, i get RuningTotal = 1.0000

FYI, in your RunningTotal, you want to frame the query by including a Rows clause

ORDER BY a.datalc, a.cm ASC 
ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW

It would appear that you have different ORDER BY clauses for your RunningTotal vs RowNum and LastPCM fields.  This will impact the outcome.

No, there are no functions in the code.  Those are simply SQL Sentry Plan Explorer getting creative with its anonymisation of the code.

Here is a list of Some Common Date Routines by Lynn Pettis

If you are using SQL2022, you can use the DATETRUNC function for these kind of calculations.

This proc takes the current datetime and does a whole lot of unnecessary calculations to reduce it to 01-JAN-1900

You execute this proc as follows

DECLARE @ResultDate datetime;

EXEC dbo.smGetMinDate...

What is the data type of DH.OPENING_HOUR_H?

Please provide samples of the data in the field

The following SQL solution should get you there

DECLARE @ReportDate   date = '2022-06-05';
DECLARE @ReportMonths int = 6; -- This value will be the number of months...

You can always use EXCEPT

SELECT ID1 FROM A1
EXCEPT
SELECT ID2 FROM A2

I would rather use

WHERE CAST(date AS  TIME) >= '00:00:00'
  AND CAST(date AS  TIME) < '06:00:00'