Find groups with matching rows

Question

I have a table of people (CarOwners) and the types of cars they own

+-------+-------+
| Name  | Model |
+-------+-------+
| Bob   | Camry |
| Bo         


        

Answer 1

One way to do this is comparing the ordered concatenated model value for each name.

with cte as (
select name,model,
     STUFF((
          SELECT ',' + t2.model
          FROM t t2
          WHERE t1.name=t2.name
          ORDER BY model
          FOR XML PATH(''), TYPE).value('.', 'VARCHAR(MAX)'), 1, 1, '') concat_value
from t t1 
) 
select distinct x2.name,x2.model
from cte x1
join cte x2 on x1.concat_value=x2.concat_value and x1.name<>x2.name
where x1.name='Kevin'

If your version of SQL Server supports STRING_AGG, the query can be simplified as

with cte as (
    select name,model,
         STRING_AGG(model,',') WITHIN GROUP(ORDER BY model) as concat_value
    from t t1 
    ) 
select distinct x2.name,x2.model
from cte x1
join cte x2 on x1.concat_value=x2.concat_value and x1.name<>x2.name
where x1.name='Kevin'