All right. How can we use these functions in our queries? We can use them to find facts which took place in the last week, last month etc. Take a look:
SELECT id FROM flight WHERE date > CURRENT_DATE - INTERVAL '7' DAY;
The above query will find all flights which took place in the last 7 days.
We use the structure INTERVAL 'x' UNIT where x is the number and UNIT is SECOND, MINUTE, HOUR, DAY, MONTH or YEAR. Our database takes the current date and puts it back 7 days.
Find the id of all the aircraft which were produced earlier than 3 months ago.
Use CURRENT_DATE - INTERVAL '3' MONTH to get the date 3 months ago.
