04 Functions - Aggregate

COUNT :   returns the NUMBER OF ROWS that satisfy the condition IN the WHERE clause.
SUM :    returns the SUM OF ALL VALUES IN a COLUMN
AVG :    computes the average OF a COLUMN
MAX :    returns the largest VALUE IN a COLUMN , use MAX
MIN :    returns the lowest member OF a COLUMN
VARIANCE:  returns the square OF the standard deviation
STDDEV:   returns the standard deviation OF a COLUMN OF numbers