The ANSI SQL:2011 window feature provides a way to dynamically define a subset of data, or window, in an ordered relational database table. A window is specified by the OVER() phrase, which can include the following clauses inside the parentheses:
To see the syntax for the OVER() phrase and the associated clauses, see Window Aggregate Functions.
The window specification can also be applied to a user-defined aggregate function. For details, see SQL UDF.