A Glance at the Window Functions

Window Functions Introduced in SQL 2005 Enhanced in SQL 2012 So-called because they operate on a defined portion of a resultset, called a Window

Basic syntax () OVER (PARTITION BY ORDER BY ) The partition defines the window The order by defines the order of rows within the window

First set of Window functions Row_Number() Rank() Dense_Rank() Ntile( )

PARTITION BY Category ORDER BY Points

Second set of Window functions Lead (Offset) Lag (Offset)

PARTITION BY Category ORDER BY Points

Aggregate Enhancements ( ) OVER (PARTITION BY ORDER BY ROWS BETWEEN AND ) Applies to Sum, Avg, Count, Min, Max

PARTITION BY Category ORDER BY Points ROWS BETWEEN 2 PRECEEDING AND CURRENT ROW