COUNT
COUNT returns the number of rows within a partition.
Syntax
COUNT ( [DISTINCT | ALL ] expression) OVER (window_clause)
or
COUNT (*) OVER (window_clause)
Remarks
• Without a window clause, COUNT is a simple aggregate function. (See
COUNT.)
Example
You want to count the total number of employees by hire date. Use a query like the following:
COUNT (*) OVER (ORDER BY hire_date)
This query first orders employees by hire date, and then applies COUNT (*).