-- =============================================
-- 售后退货申请：支持客户名称文本输入（不关联客户档案）
--
-- 变更：after_sale_return 增加 customer_name 列
--   customer_id 保持可选（未关联客户档案时为 NULL）
-- 脚本可重复执行（幂等）
-- =============================================
SET NAMES utf8mb4;

SET @sch := DATABASE();

SET @exists := (SELECT COUNT(*) FROM information_schema.COLUMNS
    WHERE TABLE_SCHEMA = @sch AND TABLE_NAME = 'after_sale_return' AND COLUMN_NAME = 'customer_name');
SET @sql := IF(@exists = 0,
    'ALTER TABLE `after_sale_return` ADD COLUMN `customer_name` varchar(200) DEFAULT NULL COMMENT ''客户名称（文本）'' AFTER `customer_id`',
    'SELECT ''customer_name 已存在，跳过'' AS msg');
PREPARE stmt FROM @sql; EXECUTE stmt; DEALLOCATE PREPARE stmt;

-- 客户编号改为可空（支持只填客户名称、不关联客户档案）
ALTER TABLE `after_sale_return` MODIFY COLUMN `customer_id` bigint DEFAULT NULL COMMENT '客户编号（可空）';

-- 核对
SELECT COLUMN_NAME, COLUMN_TYPE, IS_NULLABLE, COLUMN_COMMENT
FROM information_schema.COLUMNS
WHERE TABLE_SCHEMA = @sch AND TABLE_NAME = 'after_sale_return' AND COLUMN_NAME = 'customer_name';

SELECT '退货申请客户名称字段初始化完成' AS result;