SQL: How to order values inside group by

Posted by Denis Yaremov on Stack Overflow See other posts from Stack Overflow or by Denis Yaremov
Published on 2011-06-22T01:41:59Z Indexed on 2011/06/22 8:22 UTC
Read the original article Hit count: 165

Filed under:

mysql

|

sql

|

sql-server

|

greatest-n-per-group

Consider the following MS SQL Server table:

  ID  |   X   |   Y
------+-------+-------
   1  |   1   |   1
   2  |   1   |   2
   3  |   1   |   3
   4  |   2   |   40
   5  |   2   |   500
   6  |   3   |   1
   7  |   3   |   100
   8  |   3   |   10

I need to select the ID of the row that has the maximum value of Y grouped by x, i.e:

  ID  |   X   |   Y
------+-------+-------
   3  |   1   |   3
   5  |   2   |  500
   7  |   3   |  100

The query will be nested several times so an optimal performance solution is required...

Thank you!

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