How to generate IDs based on column values - sql-server

Question

I will provide examples and code where I can. Assume everything except [CycleStart] and [CycleEnd] datatypes are Varchar, I'm not too fussed about this at this stage.
Table A consists of the following RAW sample data:
+-------+---------+----------------+------------+------------+
| JobID | JobName | CycleDesc | CycleStart | CycleEnd |
+-------+---------+----------------+------------+------------+
| 10003 | Run1 | January 2019 | 31/12/2018 | 31/12/2018 |
| 10005 | Run2 | December 2018 | 31/12/2017 | 31/11/2018 |
| 10006 | Run3 | March 2019 | 31/12/2018 | 31/02/2019 |
| 10007 | Run4 | September 2019 | 31/12/2018 | 31/09/2019 |
| 10008 | Run5 | November 2019 | 31/12/2018 | 31/10/2019 |
+-------+---------+----------------+------------+------------+
Table B consists of the following sample data and the code used to generate this data is below:
+-------+---------+---------+
| JobID | PeriodID | Entity |
+-------+---------+---------+
| 10003 | 202101 | XYZ1 |
| 10003 | 202112 | XYZ2 |
| 10007 | 202008 | XYZ3 |
| 10007 | 202003 | XYZ4 |
| 10008 | 201904 | XYZ5 |
+-------+----------+--------+
Declare #Counter3 INT
SELECT #Counter3=1
WHILE #Counter3 <= 1000
BEGIN
INSERT INTO [dbo].[TableB]
SELECT
FLOOR(RAND()*(33979-1+1))+1 [JobID]
,CAST(ROUND(((2021 - 2019 -1) * RAND() + 2020), 0) AS VARCHAR) + RIGHT('0'+CAST(FLOOR(RAND()*(12-1+1))+1 AS VARCHAR),2) [PeriodID]
,FLOOR(RAND()*(23396-1+1))+1 [Entity]
The issue lies within Table B column [PeriodID]. This column represents an ID generated from [CycleStart] in Table A e.g. 31/12/2018 = 201812 (YYYYMM).
What I want to show in Table B is a Period ID for each Job ID but show EACH month + 30 years ahead of the [CycleStart] date. Example table of what I am looking to achieve:
+-------+---------+---------+
| JobID | PeriodID | Entity |
+-------+---------+---------+
| 10006 | 201812 | XYZ1 |
| 10006 | 201901 | XYZ2 |
| 10006 | 201902 | XYZ3 |
| 10006 | 201903 | XYZ4 |
| 10006 | 201904 | XYZ5 |
| 10006 | 201905 | XYZ5 |
| 10006 | 201906 | XYZ5 |
| 10006 | 201907 | XYZ5 |
| ... | +30yrs | ... |
| 10006 | 204812 | XYZ5 |
+-------+----------+--------+
How can I achieve this? Currently I am just randomly generating IDs which is not related to the [CycleStart] date and therefore just skewing my data but this is the only way I can think of doing it.

Answer 1

The best way is to create a calendar table / date dimension. You can use this table to solve this issue, and reuse it for other problems later. (Search online for some examples on how to build one).
If you have this table then you only need to join this table and that's it.
e.g.
INSERT INTO TableB ( JobID , PeriodID)
SELECT DISTINCT A.JobID , D.TheYear * 100 + D.TheMonth
FROM tableA A
JOIN myDateTable D
ON D.TheDate BETWEEN CONVERT(date , A.CycleStart , 103) AND DATEADD(YEAR,30, CONVERT(date , A.CycleStart , 103));