Plain functions can be used in any RAQL query clause. You may use any Presto built-in plain function (see Built-In RAQL Functions for a list) or user-defined plain functions that you or other Presto developers have added.

You can find a simple example of using plain functions in a Where clause in Use Plain Functions to Update, Select or Sort Rows. See also Comparing Dates or Numbers for an example of using casting functions in Where clauses.

This example query uses nested functions to select manufacturing plants that are in the southern hemisphere, by comparing the latitude in the data: