Take a value from another row

CREATE TABLE orders AS SELECT * FROM (VALUES
  (1,  'Alice Ng',      'north', DATE '2026-01-03', 120.00, 'widget', 'a|b',   '{"channel":"web","items":[1,2]}'),
  (2,  'alice ng',      'north', DATE '2026-01-05',  80.50, 'gadget', 'b',     '{"channel":"shop","items":[3]}'),
  (3,  'Bob  Okafor',   'south', DATE '2026-01-05', 300.00, 'widget', 'a|c',   '{"channel":"web","items":[4,5,6]}'),
  (4,  'Carla Díaz',    'east',  DATE '2026-01-09',  NULL,  'gizmo',  NULL,    '{"channel":"web","items":[]}'),
  (5,  'Bob Okafor',    'south', DATE '2026-01-12',  45.25, 'gadget', 'c',     '{"channel":"phone","items":[7]}'),
  (6,  'Dev Patel',     'west',  DATE '2026-01-12', 510.00, 'widget', 'a',     '{"channel":"web","items":[8,9]}'),
  (7,  'Carla Diaz',    'east',  DATE '2026-01-20',  99.99, 'gizmo',  'b|c',   '{"channel":"shop","items":[10]}'),
  (8,  'Dev Patel',     'west',  DATE '2026-02-02', 510.00, 'widget', 'a',     '{"channel":"web","items":[8,9]}'),
  (9,  'Eve Larsen',    NULL,    DATE '2026-02-03',  15.00, 'gadget', NULL,    '{"channel":"web","items":[11]}'),
  (10, 'Alice Ng',      'north', DATE '2026-02-10', 220.00, 'gizmo',  'a|b|c', '{"channel":"phone","items":[12,13]}')
) t(order_id, customer, region, order_date, amount, product, tags, meta);

CREATE TEMP TABLE result AS
SELECT product, order_id, amount,
       lag(amount) OVER w AS previous_amount,
       lead(amount) OVER w AS next_amount,
       round(amount / lag(amount) OVER w - 1, 4) AS change,
       first_value(amount) OVER whole AS first_amount,
       last_value(amount) OVER whole AS last_amount,
       nth_value(amount, 2) OVER whole AS second_amount
FROM orders
WHERE amount IS NOT NULL
WINDOW w AS (PARTITION BY product ORDER BY order_date, order_id),
       whole AS (PARTITION BY product ORDER BY order_date, order_id ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING);
SELECT * FROM result ORDER BY product, order_id;
SELECT CASE WHEN ((SELECT list(previous_amount ORDER BY order_id) FROM result WHERE product = 'widget') IS NOT DISTINCT FROM [NULL, 120.00, 300.00, 510.00] AND (SELECT list(next_amount ORDER BY order_id) FROM result WHERE product = 'widget') IS NOT DISTINCT FROM [300.00, 510.00, 510.00, NULL] AND (SELECT list(change ORDER BY order_id) FROM result WHERE product = 'widget') IS NOT DISTINCT FROM [NULL, 1.5, 0.7, 0.0] AND (SELECT list(change ORDER BY order_id) FROM result WHERE product = 'gadget') IS NOT DISTINCT FROM [NULL, -0.4379, -0.6685] AND (SELECT list(change ORDER BY order_id) FROM result WHERE product = 'gizmo') IS NOT DISTINCT FROM [NULL, 1.2002] AND (SELECT (first_amount, last_amount, second_amount) FROM result WHERE order_id = 6) = (120.00, 510.00, 300.00) AND (SELECT (first_amount, last_amount, second_amount) FROM result WHERE order_id = 5) = (80.50, 15.00, 45.25)) THEN 'as expected' ELSE error('the previous, next, first, last and second amounts or the change from the previous order were not the expected values per product') END AS verdict;