Select top 1 row with aggregate function - sql

Question

I have data in table like this:
UserData table:
|ID| Name | TeamName |
| 1| Peter | Alpha |
| 1| Peter | Beta |
| 1| Peter | Gamma |
| 2| Mary | Gamma |
| 2| Mary | Omega |
| 3| John | Kappa |
| 3| John | Delta |
Combinations of Name and TeamName are always unique. I need for each unique ID and Name get the top 1 TeamName and number of Team relations, like this:
table #FinalTable
|ID| Name | TeamName | NumberOfRelations |
| 1| Peter | Alpha | 3 |
| 2| Mary | Gamma | 2 |
| 3| John | Kappa | 2 |
Question - is there a way of doing this in one query, or do I have to use temporary tables for selection top 1 team and for counting number of relations and then select data indo separate final table?
I tried something like this:
;WITH cte AS
(
SELECT *, ROW_NUMBER() OVER (PARTITION BY ID ORDER BY TeamName Asc) AS rn
FROM UserData
)
SELECT * into #tempTable1
FROM cte
WHERE rn = 1
and this:
insert into #tempTable2 (ID, Name, NumberOfRelations)
select ID, Name, count(*) as NumberOfRelations
from UserData
group by ID, Name
...and then selecting data from two temp tables.
I wonder if there's more simple way of doing it.

Answer 1

For SQLserver:
You don't have order by,so i choose one below...
select top 1 with ties id,playen,count(id) over (partition by id,playen) as countt
,temaname
from #temp t1
order by row_number() over (partition by id,playen order by id,playen,temaname)
Output:
id playen countt temaname
1 Peter 3 Alpha
2 Mary 2 Gamma
3 John 2 Delta

Answer 2

Assuming this is SQL Server try this :
Select t.ID, t.Name, team.TeamName, count(t.TeamName) countt
from #temp t join
(Select id, TeamName, Row_Number() over (Partition By ID Order By TeamName asc) as rn
from #temp) team on (team.ID = t.ID and team.rn=1)
Group by t.ID, t.Name, team.TeamName

Answer 3

SQL tables represent unordered sets. There is no first team name, unless a column specifies the ordering. You don't seem to have such a column.
If you had such a column:
WITH cte AS (
SELECT ud.*,
ROW_NUMBER() OVER (PARTITION BY ID ORDER BY ??) as seqnum,
COUNT(*) OVER (PARTITION BY ID) as cnt
FROM UserData ud
)
SELECT cte.*
FROM cte
WHERE seqnum = 1;
Note the ??. This is to specify the ordering for getting the team name. Depending on the database, you can use NULL or (SELECT NULL) to get an arbitrary team name.