感觉Mybatis用Map接收结果集挺强的

1、Map接收需要指定MapKey,通常为主键

    /**
     * 销售榜单
     * @param year
     * @param month
     * @return
     */
    @MapKey("id")
    List<Map<String, Object>> salesList(@Param("year") String year,@Param("month") String month);

2、分组查询，根据产品名称分组。

    <!--销售榜单-->
    <select id="salesList" resultType="java.util.Map">
        select products.name,SUM(orderitem.buynum) as totalsalnum
        from orders,products,orderItem
        where orders.id=orderItem.order_id
        and products.id=orderItem.product_id
        and orders.paystate=1
        and year(ordertime)=#{year}
        and month(ordertime)=#{month}
        group by products.name
        order by totalsalnum desc
    </select>

3、年函数，月函数

3.1、测试SQL

 SELECT month(orders.ordertime) from orders;
 SELECT year(orders.ordertime) from orders;
SELECT orders.ordertime from orders;

3.2、结果

4、测试

    @Test
    public void salesList(){
        //select products.name,SUM(orderitem.buynum) as totalsalnum
        // from orders,products,orderItem
        // where orders.id=orderItem.order_id and products.id=orderItem.product_id
        // and orders.paystate=1
        // and year(ordertime)=? and month(ordertime)=?
        // group by products.name
        // order by totalsalnum desc

        //Parameters: 2016(String), 2(String)

        List<Map<String, Object>> mapList = productDao.salesList("2016", "2");
        mapList.forEach(map-> {
            Set<String> keySet = map.keySet();
            keySet.forEach(key-> System.out.println(key +"------"+ map.get(key)));
            Object name = map.get("name");
            //name------培育男孩
            //totalsalnum------1
            //name------学会宽容
            //totalsalnum------1
        });