The WINDOW clause can be used to explicitly name a window, for example to avoid repetitive or confusing expression.

A named window can be used

1. in the OVER clause to reference a window definition, e.g. OVER window_name

2. as a base window of another named or inline (OVER) window, if it is not a window with a frame (ROWS or RANGE clauses)

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   Note

   A window with a base windows cannot have PARTITION BY, nor override the ordering (ORDER BY) of a base window.