SQL Query Get the Next ID - sql

Question

I am working on a problem where I need to get the next available Category for a gamer. If the gamer has reached the final Category (Shooter in below image) then I will need to go back to the start of the table and go to the next one available.
Below is a list of Category:
Below is a list of gamers and what their last Category_ID was:
Finally, below is the data I will be using to work with
Now I need to find the next Category_ID for each gamer using the data table. If a Gamer has reached the last Category_ID (ID 4 in this case and Gamer C) then it will reset back to top like 1 however Gamer C will pick Category 2 as there is no one for that Gamer.
How can I pick the next Category available using the data table for each gamer while keeping in mind of resetting back to top if reached end?
Below is a code example of the problem:
DECLARE #Category AS TABLE
(
Category_ID INT IDENTITY(1,1) ,
Description VARCHAR(255)
)
INSERT INTO #Category
VALUES('Sports'), ('Adventure'), ('Action'), ('Shooter')
DECLARE #Gamer AS TABLE
(
Username VARCHAR(255) ,
Last_Category_ID INT
)
INSERT INTO #Gamer
VALUES('Gamer A', 1), ('Gamer B', 2), ('Gamer C', 4), ('Gamer D', 3)
DECLARE #Data AS TABLE
(
Username VARCHAR(255) ,
Play_At DATETIME ,
Category_ID INT
)
INSERT INTO #Data
VALUES('Gamer A', GETDATE() -1, 1), ('Gamer B', GETDATE() -1, 2), ('Gamer A', GETDATE() -1, 3), ('Gamer D', GETDATE() -1, 3), ('Gamer C', GETDATE() -1, 2)
SELECT * FROM #Category
SELECT * FROM #Gamer
SELECT * FROM #Data

Answer 1

If I understand correctly, you want the next unused category id for each gamer. And then to start over when all are done.
Here is an approach:
For each gamer, get the maximum current category.
For each category, get the next category.
Get the first category as well.
When there is no next category use the first.
This is a good opportunity to use lateral joins:
select g.*, coalesce(cn.category_id, cf.category_id)
from #gamers g outer apply
(select max(category_id) as max_category_id
from #data d
where d.username = g.username
) c outer apply
(select top (1) cn.category_id
from #categories cn
where cn.categoryid > c.max_categoryid
) cn cross join
(select min(cf.category_id) as categoryi_d
from #categories cf
) cf;
Here is a db<>fiddle.

Answer 2

I'm not 100% clear on if your #Data table represents the starting category however this might be what you need, if not by all means please clarify with some clear expected results for the sample data.
Using an apply to determine the starting category for each user (if indeed that's what your description entails) and another to get the maximum possible category, select the username and, using a case expression, the corresponding next category name or the starting category if it's already the max category.
select
Username,
( select description
from #category c
where c.category_Id=case when Last_Category_ID<m.Id then Last_Category_ID + 1 else startcat.Id end
) NextCategory
from #gamer g
outer apply (
select min(category_id) Id
from #data d
where d.username=g.Username
)startcat
outer apply (
select Max(category_Id) Id
from #category
)m