物联网问题解决，只差最后测试完善

tradeCattle/fix_delivery_id_relation.sql

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+-- 修改iot_device_data表的delivery_id字段，关联到delivery表的主键
+-- 将delivery_id改为整数类型，关联delivery表的id字段
+
+ALTER TABLE `iot_device_data` 
+MODIFY COLUMN `delivery_id` int(11) DEFAULT NULL COMMENT '装车订单ID，关联delivery表主键';
+
+-- 添加外键约束（可选）
+-- ALTER TABLE `iot_device_data` 
+-- ADD CONSTRAINT `fk_iot_device_delivery` 
+-- FOREIGN KEY (`delivery_id`) REFERENCES `delivery`(`id`) ON DELETE SET NULL;