Syntaxe UPDATE je:
[ WITH [ RECURSIVE ] with_query [, ...] ] UPDATE [ ONLY ] table [ [ AS ] alias ] SET { column = { expression | DEFAULT } | ( column [, ...] ) = ( { expression | DEFAULT } [, ...] ) } [, ...] [ FROM from_list ] [ WHERE condition | WHERE CURRENT OF cursor_name ] [ RETURNING * | output_expression [ [ AS ] output_name ] [, ...] ]
Ve vašem případě si myslím, že chcete toto:
UPDATE vehicles_vehicle AS v
SET price = s.price_per_vehicle
FROM shipments_shipment AS s
WHERE v.shipment_id = s.id