Functions are similar to operators in that they manipulate data items and return a result. Functions differ from operators in the format of their arguments. This format enables functions to operate on zero, one, two, or more arguments:

function(argument 1, argument 2, ...)

There are three types of functions:

  1. Single-row functions: these functions return a single row for every row of a queried table or view.

  2. Aggregate functions

  3. Analytic functions