Full years from a birthdate - which expression works?

Question

Accepted Answer

AGE(timestamp) in PostgreSQL returns the interval between the given timestamp and now (e.g. '30 years 4 months 12 days'). EXTRACT(YEAR FROM AGE(birth_date)) then pulls the year component - the number of complete years elapsed. CURRENT_DATE - birth_date gives days, not years. DATEDIFF is a MySQL/SQL Server function, not standard PostgreSQL.