- demo 项目，增加提交订单接口

demo/demo-business/src/main/resources/mapper/DemoProductMapper.xml

@@ -0,0 +1,12 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
+<mapper namespace="cn.iocoder.mall.demo.business.dao.DemoProductMapper">
+
+    <update id="updateQuantityReduce">
+        UPDATE product
+        SET quantity = quantity - #{quantity}
+        WHERE id = #{id}
+        AND quantity >= #{quantity}
+    </update>
+
+</mapper>