Deleting rows from a table when i pass a string - sql

Question

Hello everyone i want to create a procedure that receives a int and a string with the ID's when they are like this:
Int CompeteID = 1
String TeamIDs = "1,8,9"
Meaning there are 3 TeamIDs, TeamID = 1, TeamID = 8 and TeamID = 9.
Here is my DBModel: https://i.gyazo.com/7920cca8000436cfe207353aaa7d172f.png
So what i want to do is to Insert on TeamCompete, the SportID and CompeteID when there are no equal SportID and CompeteID.
Like this:
TeamCompeteID TeamID CompeteID
1 1 1
4 8 1
5 9 1
6 8 1 <---- Can't do this
But i also want to delete from TeamCompete the TeamIDs i dont pass onto the procedure for example:
TeamCompeteID TeamID CompeteID
1 1 1
2 3 1 <---- Delete this
3 4 1 <---- Delete this
But I don't want to delete the TeamCompete's that are on the Event table...
Example:
EventID TeamCompeteID
5 3 <---- Can't delete TeamCompeteID 3
-- even though i didn't past it on TeamIDs
I hope you understanded my explanation.

Answer 1

First and foremost, passing data in this manner is very much a bad idea. You should really try to normalise your data and have one value in each field.
If however, you cannot avoid this, I would recommend you use a string splitting function such as Jeff Moden's if you are on a SQL Server version prior to 2016 (the string_split is built into SQL Server 2016) which returns a table you can join to from a given string and delimiter.
Using Jeff's function above:
select *
from dbo.DelimitedSplit8K('1,8,9',',')
Results in:
+------------+------+
| ItemNumber | Item |
+------------+------+
| 1 | 1 |
| 2 | 8 |
| 3 | 9 |
+------------+------+
So to use with your table:
declare #t table(CompeteID int,TeamID nvarchar(10));
insert into #t values(1,'1,8,9');
select t.CompeteID
,s.Item
from #t t
cross apply dbo.DelimitedSplit8K(t.TeamID,',') s
Results in:
+-----------+------+
| CompeteID | Item |
+-----------+------+
| 1 | 1 |
| 1 | 8 |
| 1 | 9 |
+-----------+------+
You can then use this table in the rest of your update/insert/delete logic.