Unix Timestamps in SQL

-- PostgreSQL:
SELECT EXTRACT(EPOCH FROM NOW())::BIGINT;               -- Current epoch
SELECT TO_TIMESTAMP(1710000000) AT TIME ZONE 'UTC';        -- Convert to UTC timestamp

-- MySQL:
SELECT UNIX_TIMESTAMP();                                -- Current epoch
SELECT FROM_UNIXTIME(1710000000);                          -- Convert to datetime

-- SQLite:
SELECT strftime('%s', 'now');                          -- Current epoch
SELECT datetime(1710000000, 'unixepoch');                  -- Convert to datetime