ALTER TABLE drivers ADD COLUMN assigned_trailer TEXT NOT NULL DEFAULT '';
ALTER TABLE driver_assignment_requests ADD COLUMN from_trailer_id TEXT NOT NULL DEFAULT '';
ALTER TABLE driver_assignment_requests ADD COLUMN to_trailer_id TEXT NOT NULL DEFAULT '';

CREATE INDEX idx_drivers_assigned_trailer
ON drivers(assigned_trailer);

CREATE UNIQUE INDEX idx_drivers_one_active_trailer
ON drivers(assigned_trailer)
WHERE assigned_trailer <> '' AND status = 'Actif';

PRAGMA optimize;