Analytic & Aggregate Function -Count(*)
COUNT as an Aggregate Function
The COUNT aggregate function returns the number of rows in a set. As an aggregate function it reduces the number of rows, hence the term "aggregate". If the data isn't grouped we turn the nof rows in the EMP table to a single row with the aggregated values. Using "*" or a mandatory column as a parameter returns the total number of rows in the set. Using an optional column returns the total number of rows with a non-null value in that column.
Analytic returns multiple rows
