12.2.1 数据层

一般一个表对应着一个类.

12.2.1.1 数据层的mapper接口

import java.util.List;
import java.util.Map;

public interface OrderMapper {

    /**
     * 获取订单总的销售额
     *
     * @param date
     * @return
     */
    double getOrderAmountTotal(String date);

    /**
     * 获取每小时的销售额明细
     *
     * @param date
     * @return
     */
    List<Map> getOrderAmountHour(String date);

}

12.2.1.2 数据层的 sql

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper SYSTEM "http://mybatis.org/dtd/mybatis-3-mapper.dtd" >
<!--namespace 对应前面定义的接口-->
<mapper namespace="com.atguigu.gmall0225publisher2.mapper.OrderMapper">
    <!--对应前面接口中的方法,  标签内写响应的查询语句, 查询的接口会赋值给这个方法的返回值-->
    <select id="getOrderAmountTotal" resultType="java.lang.Double">
        select sum(total_amount) sum from gmall_order_info where create_date=#{date}
    </select>

    <!--分时明细-->
    <select id="getOrderAmountHour" resultMap="orderAmountHourList">
        select create_hour, sum(total_amount) sum from gmall_order_info  where create_date=#{date} group by create_hour
    </select>
    <resultMap id="orderAmountHourList" type="java.util.Map" autoMapping="true">

    </resultMap>

</mapper>