mybatis多表查询

sanxiangzhili

# 复杂查询

## 多对一查询

### 按照查询嵌套处理

```xml
<mapper namespace="com.hzj.mapper.TeachScheduleMapper">
    <select id="getTeachScheduleList" resultMap="teacheScheduleMap">
        SELECT * FROM studentdb.teach_schedule;
    </select>

    <resultMap id="teacheScheduleMap" type="ts">
        <result property="courseId" column="course_id"/>
        <result property="courseTime" column="course_Time"/>
        <result property="courseWeek" column="course_week"/>
        <result property="roomId" column="room_id"/>
        <result property="deptId" column="dept_id"/>
        <association property="teacherInfo" javaType="ti" column="teacher_id" select="getTeacherInfo"/>
    </resultMap>

    <select id="getTeacherInfo" resultType="ti">
        SELECT * FROM studentdb.teacher_info WHERE id=#{id};
    </select>

</mapper>
```

- teacherInfo为该需要多表查询pojo类中需要的其他pojo类信息的pojo类字段，ti为需要的其他pojo类，teacher_id为该pojo类对应数据库表中的外键字段，getTeacherInfo则为需要用到的子查询