Mybatis一对多查询

Posted 2020-10-05 薛小生

<resultMap type="com.neuedu.bean.tbl_dept" id="findDepartByIdMap">
        <id column="did" property="id"/>
        <result column="dept_name"  property="deptName"/>
<!--使用collection标签
　　property属性指定POJO中关联查询的属性，oftype指定关联查询的属性的类型
-->

        <collection property="empList" ofType="com.neuedu.bean.tbl_employee" >
            <id column="eid" property="id"/>
            <result column="user_name" property="userName"/>
            <result column="email" property="email"/>
            <result column="gender" property="gender"/>
            <result column="d_id" property="dId"/>
        </collection>
        

    </resultMap>
    <!-- public tbl_dept findDepartById(int id); -->
    <select id="findDepartById" resultMap="findDepartByIdMap">
        select
        d.id did,d.dept_name,e.id eid,e.user_name,e.email,e.gender,e.d_id
        from tbl_dept d
        LEFT JOIN tbl_employee e
        on d.id=e.d_id
        where d.id=#{id}
    </select>

 在POJO中将关联查询的集合设置为一个list属性

public class tbl_dept {
    private int id;
    private String deptName;
    private List<tbl_employee>empList;//关联查询的集合
    }