Select (SQL) - Window Function

Window Function

A window function in SQL:2003 is an aggregate function applied to a partition of the result set.

For example,

sum(population) OVER( PARTITION BY city )

calculates the sum of the populations of all rows having the same city value as the current row.

Partitions are specified using the OVER clause which modifies the aggregate. Syntax:

:: = OVER ( )

The OVER clause can partition and order the result set. Ordering is used for order-relative functions such as row_number.

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