The COUNT function counts unique values of a selected attribute (e.g., Employee) in a given dataset determined by the second attribute parameter (e.g., Records of Department).
SELECT COUNT(attribute, connection_point)
where connection_point is the foreign key, connecting to the data set in which the count is to take place.
COUNT of Store returns the number of different stores based on the number of distinct values of the Store attribute.
SELECT COUNT(Employee, Facts_of_Call)