一、应用场景
查询所有用户及其购买的商品
第一步
修改user,让其持有orders的集合list
第二步
修改orders让其持有orderdetail集合
第三步
修改orderdetail,让其持有item对象
Mapper.xml配置文件
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<resultMap type="com.james.po.User" id="selectUserAllItemResultMap"> <id column="user_id" property="id"/> <result column="username" property="userName"/> <result column="sex" property="sex"/> <result column="address" property="address"/> <collection property="ordersList" ofType="com.james.po.Orders"> <id column="id" property="id"/> <result column="user_id" property="userId"/> <result column="number" property="number"/> <result column="createtime" property="createtime"/> <result column="note" property="note"/> <collection property="orderdetails" ofType="com.james.po.Orderdetail"> <id column="orderdetail_id" property="id"/> <result column="items_id" property="itemsId"/> <result column="items_num" property="itemsNum"/> <result column="orders_id" property="ordersId"/> <association property="items" javaType="com.james.po.Items"> <id column="items_id" property="id"/> <result column="items_name" property="name"/> <result column="items_detail" property="detail"/> <result column="items_price" property="price"/> </association> </collection> </collection> </resultMap>
<select id="selectUserAllItem" resultMap="selectUserAllItemResultMap"> SELECT orders.*, USER.username, USER.sex, USER.address, orderdetail.id orderdetail_id, orderdetail.items_id, orderdetail.items_num, orderdetail.orders_id, items.name items_name, items.detail items_detail, items.price items_price FROM orders,USER,orderdetail,items WHERE orders.user_id = user.id AND orderdetail.orders_id=orders.id AND orderdetail.items_id = items.id </select>
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