-- 2026-09-29 海外退货签收 SKU 箱数增量
-- MySQL 8.0+；目标数据库：baiyue_lastleg
-- 可重复执行，不修改既有业务数据。

SET NAMES utf8mb4;
USE baiyue_lastleg;

SET @ddl = IF(
  EXISTS (
    SELECT 1 FROM information_schema.tables
    WHERE table_schema = DATABASE() AND table_name = 'll_return_receipt_item'
  )
  AND NOT EXISTS (
    SELECT 1 FROM information_schema.columns
    WHERE table_schema = DATABASE()
      AND table_name = 'll_return_receipt_item'
      AND column_name = 'box_count'
  ),
  'ALTER TABLE ll_return_receipt_item ADD COLUMN box_count BIGINT NULL COMMENT ''本次 SKU 对应箱数'' AFTER received_quantity',
  'SELECT 1'
);
PREPARE stmt FROM @ddl;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;

SELECT DATABASE() AS target_database, 'll_return_receipt_item.box_count' AS updated_column;