Functions for manipulating Data in PostgreSQL

/* Look at system database about information about the tables, columns n our database */
SELECT *
FROM INFORMATION_SCHEMA.TABLES
WHERE table_schema = 'public'

SELECT * 
FROM INFORMATION_SCHEMA.COLUMNS

SELECT *
FROM INFORMATION_SCHEMA.COLUMNS
WHERE table_name = 'customer'

SELECT create_date FROM dvdrentals.customer

SELECT column_name, data_type
FROM INFORMATION_SCHEMA.COLUMNS
WHERE column_name = 'rental_date' AND table_name='rental'

SELECT column_name, data_type
FROM INFORMATION_SCHEMA.COLUMNS
WHERE column_name IN ('rental_date', 'return_date') AND table_name='rental';

/* Add 3 days to rental date and see the difference between return date and expected return date */

SELECT rental_date, return_date,
	rental_date + INTERVAL '3 days' AS expected_return_date,
    CASE WHEN return_date <= rental_date + INTERVAL '3 days' THEN 'On time'
    	ELSE 'Overdue' END AS return_outcome
FROM dvdrentals.rental