Fetch the row which has the Max value for a column in SQL Server
I found a question that was very similar to this one, but using features that seem exclusive to Oracle. I'm looking to do this in SQL Ser开发者_StackOverflowver.
I have a table like this:
MyTable
--------------------
MyTableID INT PK
UserID INT
Counter INT
Each user can have multiple rows, with different values for Counter
in each row. I need to find the rows with the highest Counter
value for each user.
How can I do this in SQL Server 2005?
The best I can come up with is a query the returns the MAX(Counter)
for each UserID
, but I need the entire row because of other data in this table not shown in my table definition for simplicity's sake.
EDIT: It has come to my attention from some of the answers in this post, that I forgot an important detail. It is possible to have 2+ rows where a UserID can have the same MAX counter value. Example below updated for what the expected data/output should be.
With this data:
MyTableID UserID Counter
--------- ------- --------
1 1 4
2 1 7
3 4 3
4 11 9
5 11 3
6 4 6
...
9 11 9
I want these results for the duplicate MAX values, select the first occurance in whatever order SQL server selects them. Which rows are returned isn't important in this case as long as the UserID/Counter pairs are distinct:
MyTableID UserID Counter
--------- ------- --------
2 1 7
4 11 9
6 4 6
I like to use a Common Table Expression for that case, with a suitable ROW_NUMBER() function in it:
WITH MaxPerUser AS
(
SELECT
MyTableID, UserID, Counter,
ROW_NUMBER() OVER(PARTITION BY userid ORDER BY Counter DESC) AS 'RowNumber'
FROM dbo.MyTable
)
SELECT MyTableID, UserID, Counter
FROM MaxPerUser
WHERE RowNumber = 1
THat partitions the data over the UserID, orders it by Counter (descending) for each user, and then labels each of the rows starting with 1 for each user. Select only those rows with a 1 for rownumber and you have your max. values per user.
It's that easy :-) And I get results something like this:
MyTableID UserID Counter
2 1 7
6 4 6
4 11 9
Only one entry per user, no matter how many rows per user happen to have the same max value.
I think this will help you.
SELECT distinct(a.userid), MAX(a.counterid) as counterid
FROM mytable a INNER JOIN mytable b ON a.mytableid = b.mytableid
GROUP BY a.userid
There are several ways to do this, take a look at this Including an Aggregated Column's Related Values Several methods are shown including the performance differences
Here is one example
select t1.*
from(
select UserID, max(counter) as MaxCount
from MyTable
group by UserID) t2
join MyTable t1 on t2.UserID =t1.UserID
and t1.counter = t2.counter
Try this... I'm pretty sure this is the only way to truly make sure you get one row per User.
SELECT MT.*
FROM MyTable MT
INNER JOIN (
SELECT MAX(MID.MyTableId) AS MaxMyTableId,
MID.UserId
FROM MyTable MID
INNER JOIN (
SELECT MAX(Counter) AS MaxCounter, UserId
FROM MyTable
GROUP BY UserId
) AS MC
ON (MID.UserId = MC.UserId
AND MID.Counter = MC.MaxCounter)
GROUP BY MID.UserId
) AS MID
ON (MID.UserId = MC.UserId
AND MID.MyTableId = MC.MaxMyTableId)
select m.*
from MyTable m
inner join (
select UserID, max(Counter) as MaxCounter
from MyTable
group by UserID
) mm on m.UserID = mm.UserID and m.Counter = mm.MaxCounter
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