VIP23/04maven/mybatis/target/classes/DepartmentMapper.xml

<?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="com.sf.mapper.DepartmentMapper">

    <select id="getDepartmentInfo" parameterType="integer" resultType="department">
        select * from department where dept_id = #{deptId}
    </select>

<!--    getDepartmentInfoWithEmploye方法中的  map1  对应我们<resultMap>标签中的 id属性  type 映射结果的全类名
column:对应我们数据库中的字段   property：对应我们java对象中的属性名
<id>:映射字段中的id属性
<result>：映射字段中的非id属性
collection：一对多映射标签
 ofType="employee" ：一对多的属性名的类型的全类名

-->

        <resultMap id="map1" type="com.sf.entity.Department">
            <id column="dept_id" property="deptId"></id>
            <result column="dept_name" property="deptName"></result>
            <collection property="employees" ofType="employee">
                <id column="emp_id" property="empId"></id>
                <result column="emp_name" property="empName"></result>
                <result column="salary" property="salary"></result>
            </collection>
        </resultMap>


    <select id="getDepartmentInfoWithEmployee" parameterType="integer" resultMap="map1">
        select * from department t1 , employee t2 where t1.dept_id = t2.dept_id and t1.dept_id = #{deptId}
    </select>


<!--
<collection>标签中的  column="dept_id"  ： 我们关联表的外键
                     select ： 是查询员工信息的接口
 -->

    <resultMap id="deptMap2" type="department">
        <id column="dept_id" property="deptId"></id>
        <result column="dept_name" property="deptName"></result>
        <collection property="employees" ofType="employee" column="dept_id" select="com.sf.mapper.DepartmentMapper.getEmployeeInfoByDeptId">
            <id column="emp_id" property="empId"></id>
            <result column="emp_name" property="empName"></result>
            <result column="salary" property="salary"></result>
        </collection>
     </resultMap>

<!--    分为俩步骤：
1.根据dept_id查询部门信息
2.根据的dept_id查询员工的信息
-->


    <select id="getDepartmentInfoWithEmployee2" parameterType="integer" resultMap="deptMap2">
        select * from department  where dept_id = #{deptId}
    </select>

    <select id="getEmployeeInfoByDeptId" parameterType="integer" resultType="employee">
        select * from employee where dept_id  = #{deptId}
    </select>

</mapper>