Processing Function and Data Sources

PostgreSQL embeds a very rich set of processing functions that can be used anywhere in the queries, even if most of them are more useful in the select clause. Because we see a lot of code fetching only the raw data from the RDBMS and then doing all the processing in the application code, we want to show an example query processing calendar-related information with PostgreSQL.

Functions for date and time

The following query is a showcase for extract() and to_char() functions, and it also uses the case construct. Read the documentation on date/time functions and operators for more details and functions on the same topic.