SQL Server 2012 Enhancements to Windowing Functions
Basic windowing capabilities were first provided in SQL Server 2005 with the introduction of the OVER
clause and four new ranking functions ROW_NUMBER
, RANK
, DENSE_RANK
, and NTILE
. By default, the OVER
clause produces a single window over the entire result set, but use of the optional PARTITION BY
clause lets you divide the result set up into distinct “windows,” one per partition. The ORDER BY
option for the OVER
clause provides the ability to generate cumulative calculations within each window.
In addition to the four ranking functions, SQL Server supported use of the traditional aggregate functions (SUM
, COUNT
, MIN
, MAX
, AVG
) with the OVER
clause along with the optional PARTITION BY
clause. ...
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