I have a table with something like the following:
ID Name Color
------------
1 Bob Blue
2 John Yellow
1 Bob Green
3 Sara Red
3 Sara Green
What I would like to do is return a filtered list of results whereby the following data is returned:
ID Name Color
------------
1 Bob Blue
2 John Yellow
3 Sara Red
ie I would like to return 1 row per user. (I do not mind which row is returned for the particular user - I just need that the [ID] is unique.) I have something already that works but is really slow where I create a temp table adding all the ID's and then using a "OUTER APPLY" selecting the top 1 from the same table, ie
CREATE TABLE #tb
(
[ID] [int]
)
INSERT INTO #tb
select distinct [ID] from MyTable
select
T1.[ID],
T2.[Name],
T2.Color
from
#tb T1
OUTER APPLY
(
SELECT TOP 1 * FROM MyTable T2 WHERE T2.[ID] = T1.[ID]
) AS V2
DROP TABLE #tb
Can somebody suggest how I may improve it?
Thanks
Try:
WITH CTE AS
(
SELECT ROW_NUMBER() OVER (PARTITION BY ID ORDER BY ID) AS 'RowNo',
ID, Name, Color
FROM table
)
SELECT ID,Name,color
FROM CTE
WHERE RowNo = 1
or
select
*
from
(
Select
ID, Name, Color,
rank() over (partition by Id order by sum(Name) desc) as Rank
from
table
group by
ID
)
HRRanks
where
rank = 1
If you're using SQL Server 2005 or higher, you could use the Ranking functions and just grab the first one in the list.
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