Part 104: Date Extraction & Arithmetic: EXTRACT & Date Math

Working with calendar intervals and calculating user age or tenure.

1. Date Arithmetic in PostgreSQL

-- Add 14 days to a trial period:
SELECT signup_date + INTERVAL '14 days' AS trial_expiration
FROM accounts;

-- Extracting sub-components:
SELECT 
  EXTRACT(YEAR FROM created_at) AS signup_year,
  EXTRACT(DOW FROM created_at) AS day_of_week -- 0 = Sunday
FROM accounts;

Key Takeaways

• Use EXTRACT(FIELD FROM timestamp) for granular date parts.

In Part 105, we explore Formatting Dates & Numbers: TO_CHAR & DATE_FORMAT!