mybatis两种一对多查询

ゞ浴缸里的玫瑰 2023-06-16 13:55 1阅读 0赞

1.嵌套结果查询

<?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="cn.itsource._03_one2many.DomainMapper">
      
      
      <resultMap type="cn.itsource._03_one2many.Dept" id="deptMap">
      
      
      <id property="id" column="id"/>
      <result property="name" column="name"/>
      
      
      <collection property="users" javaType="cn.itsource._03_one2many.User">
      <id property="id" column="uid"/>
      <result property="name" column="uname"/>
      <result property="password" column="password"/>
      
      </collection>
      
      </resultMap>
      
      <select id="getDepts" resultMap="deptMap">
      select d.id,d.name,u.id uid,u.name uname,u.password  from t_dept d left join t_user u on u.dept_id = d.id
      </select>
      </mapper>

2.嵌套查询

<?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="cn.itsource._03_one2many.DomainMapper">
      
      
      <resultMap type="cn.itsource._03_one2many.Dept" id="deptMap">
      <id column="id" property="id"/>
      <result column="name" property="name"/>
      
      
      <collection property="users" ofType="cn.itsource._03_one2many.User"  column="id" select="getUserByDeptId"/>
     
      </resultMap>
      
      
      <select id="getUserByDeptId" parameterType="cn.itsource._03_one2many.Dept">
      select * from t_user where dept_id=#{ id}
      </select>
      
      <select id="getDepts" resultMap="deptMap">
     select * from t_dept
      </select>
      </mapper>