The previous example showed one way to retrieve, and further process, function results. The following are a few more useful ways to call a function:

SELECT fib(25);
SELECT (flatten_application_settings('9.08.97')).*;
SELECT * FROM flatten_application_settings('9.08.97');

Any of the preceding methods will create a legal field list in PostgreSQL, which, in turn, can be used in any way the fields in a simple SELECT statement on a table are used.

The example in the previous section used the results of the flatten_application_settings() function, a source of data for an INSERT statement. The following is an example of how to use the same function as a data source for UPDATE:

UPDATE application_settings_new 
   SET full_name = flat.full_name,
       description  = flat.description,
       print_certificate = flat.print_certificate,
       show_advertisements = flat.show_advertisements,
       show_splash_screen = flat.show_splash_screen  
  FROM flatten_application_settings...