Table Functions
Table functions are methods for constructing tables.
You can use table functions in:
- FROM clause of the - SELECTquery.- The method for creating a temporary table that is available only in the current query. The table is deleted when the query finishes. 
- CREATE TABLE AS table_function() query. - It's one of the methods of creating a table. 
- INSERT INTO TABLE FUNCTION query. 
note
You can’t use table functions if the allow_ddl setting is disabled.