In database management an aggregate function is a function where the values of multiple rows are grouped together as input on certain criteria to form a single value of more significant meaning or measurement such as a set, a bag or a list. Common aggregate functions include : * Average() (i.e., arithmetic mean) * Count() * Maximum() * nanmean() (mean ignoring NaN values, also known as "nil" or "null") * Median() * Minimum() * Mode() * Sum() Aggregate functions are common in numerous programming languages, spreadsheets, and relational algebra.