-- Device-initiated unbinding is identified by device_no + binding_id.
-- Keep the most useful result if the old commandId protocol created duplicate rows.
DELETE d
FROM app_device_unbind_command d
JOIN app_device_unbind_command r
  ON r.device_no = d.device_no
 AND r.binding_id = d.binding_id
 AND (
      CASE r.command_status
          WHEN 'APPLIED' THEN 4
          WHEN 'PROCESSING' THEN 3
          WHEN 'FAILED' THEN 2
          WHEN 'STALE' THEN 1
          ELSE 0
      END > CASE d.command_status
          WHEN 'APPLIED' THEN 4
          WHEN 'PROCESSING' THEN 3
          WHEN 'FAILED' THEN 2
          WHEN 'STALE' THEN 1
          ELSE 0
      END
      OR (
          r.command_status = d.command_status
          AND r.id < d.id
      )
 );

ALTER TABLE app_device_binding
    DROP COLUMN unbind_command_id;

ALTER TABLE app_device_unbind_command
    DROP INDEX uk_app_device_unbind_command,
    DROP INDEX idx_app_device_unbind_binding,
    DROP COLUMN command_id,
    ADD UNIQUE KEY uk_app_device_unbind_binding (device_no, binding_id);