Combining specific sql query results into one string - sql

Question

I have the following query;
SELECT custom.name, instance_id
FROM table1 tb
WHERE tb.instance_id = 1111 OR tb.instance_id = 2222
This returns the following results;
test, 1111
test1, 1111
test3, 1111
tabletest, 2222
tabletest1, 2222
tabletest2, 2222
I would like the ability to match the instances_id, and combine the matching rows into a single string.
i.e.
test;test1;test3
tabletest;tabletest1;tabletest2
I can get a single string but at the moment this grabs all the results and puts it into a single string.
STUFF((
SELECT custom.name + ';'
FROM table1 tb
WHERE tb.instance_id = 1111 OR tb.instance_id = 222
FOR XML PATH(' '), TYPE.value('.', 'NVARCHAR(MAX)'), 1, 0, ' ')
this results in
test;test1;test3;tabletest;tabletest1;tabletest2
Unfortunately I cannot upgrade past sql server version 15 which perhaps limits me.

Answer 1

You need a correlation clause in the subquery. I would suggest:
SELECT v.instance_id,
STUFF((SELECT ';' + tb.name
FROM table1 tb
WHERE tb.instance_id = v.instance_id
FOR XML PATH(''), TYPE
).value('.', 'NVARCHAR(MAX)'
), 1, 1, ' '
)
FROM (VALUES (1111), (2222)) v(instance_id);
Here is a db<>fiddle.

Answer 2

Data
drop table if exists dbo.tTable;
go
create table dbo.tTable(
[name] varchar(100) not null,
instance_id int not null);
insert dbo.tTable values
('test',1111),
('test1',1111),
('test3',1111),
('test',2222),
('test1',2222),
('test2',2222);
Query
select instance_id,
stuff((select ';' + cast([name] as varchar(100))
from tTable c2
where t.instance_id = c2.instance_id
order by [name] FOR XML PATH('')), 1, 1, '') [value1]
from tTable t
group by instance_id;
Output
instance_id value1
1111 test;test1;test3
2222 test;test1;test2