MyBatis 一对多 多对一 自关联 例子

public interface IDepet {    public Dept getAll(int id);    public Dept  getAllMutlSql(int id);}

<mapper namespace="cn.hello.dao.IDepet">    <resultMap id="deptMap" type="Dept">        <id column="deptNo" property="deptNo"></id>        <result column="deptName" property="deptName"></result>        <collection property="emps" ofType="Emp">            <id column="empNo" property="empNo"></id>            <result column="empName" property="empName"></result>        </collection>    </resultMap>    <resultMap id="deptMapMutlSql" type="Dept">        <id column="deptNo" property="deptNo"></id>        <result column="deptName" property="deptName"></result>        <collection property="emps" ofType="Emp" select="selectDeptNo" column="deptNo"></collection>    </resultMap>    <!--一对多 多条SQ-->    <select id="selectDeptNo" resultType="Emp">      SELECT  * FROM emp WHERE  deptNo=#{deptNo}    </select><!--一对多 单条SQL-->     <select id="getAll" resultMap="deptMap">          select dept.deptNo,deptName,empNo,empName        from dept,emp        where dept.deptNo=emp.deptNo        and dept.deptNo=#{deptNo}     </select><!--一对多 多条SQ-->    <select id="getAllMutlSql" resultMap="deptMapMutlSql">        select deptNo,deptName        from dept        where deptNo=#{deptNo}    </select></mapper>

public interface IEmp {    public Emp SelectEmpNo(int id);    public  Emp  SelectEmpNoMutile(int id);}<mapper namespace="cn.hello.dao.IEmp">  <resultMap id="empMap" type="Emp">      <id column="empNo" property="empNo"></id>      <result column="empName" property="empName"></result>      <association property="dept" javaType="Dept">          <id column="deptNo" property="deptNo"></id>          <result column="deptName" property="deptName"></result>      </association>  </resultMap>    <resultMap id="empMapMuit" type="Emp">        <id column="empNo" property="empNo"></id>        <result column="empName" property="empName"></result>        <association property="dept" javaType="Dept" select="selectDeptNo" column="deptNo"></association>    </resultMap>    <!--多对一  多条SQL-->    <select id="selectDeptNo" resultType="Dept">       SELECT  * FROM  dept WHERE deptNo=#{deptNo}    </select>     <!--多对一 一条SQL-->    <select id="SelectEmpNo" resultMap="empMap">          select dept.deptNo,deptName,empNo,empName        from dept,emp        where dept.deptNo=emp.deptNo        and emp.empNo=#{empNo}     </select><!--多对一  多条SQL-->    <select id="SelectEmpNoMutile" resultMap="empMapMuit">         SELECT deptNo,empNo,empName         FROM  emp         WHERE  empNo=#{empNo}    </select></mapper>

public interface ICategory {    public List<Category>  getChildreByPid(int id);}<mapper namespace="cn.hello.dao.ICategory">    <!--自关联-->    <resultMap id="CateMap" type="Category">        <id column="cid" property="cid"></id>        <result column="cname" property="cname"></result>        <result column="pid" property="pid"></result>        <collection property="cates" ofType="Category" select="getChildreByPid" column="cid"></collection>    </resultMap>    <select id="getChildreByPid" resultMap="CateMap">   SELECT  * FROM  category WHERE pid=#{pid}    </select></mapper>