private Degree _degree;
        public Degree Degree
        {
            get
            {
                return _degree;
            }
            set
            {
                _degree = value;
            }
        }

    <resultMap id="com2result"  class="Account" >
      <result property="Id"           column="Account_ID"/>
      <result property="FirstName"    column="Account_FirstName"/>
      <result property="LastName"     column="Account_LastName"/>
      <result property="EmailAddress" column="Account_Email" nullValue="no_email@provided.com"/>
      <result property="Degree"  resultMapping="Account.Degree-result"/>
    </resultMap>

    <resultMap id="Degree-result"  class="Degree">
      <result property="Id"           column="Account_ID"/>
      <result property="DegreeName"    column="DegreeName"/>
    </resultMap>

    <select id="GetCom2Tables"
     resultMap="com2result">
      select Accounts.*, Degree.*
      from Accounts,Degree
      where Accounts.Account_ID = Degree.Account_ID
    </select>

这样就可以随心所欲的写自己需要的sql，性能也很好，不会出现第三种方法中的1+n条的查询语句了。

    本文转自永春博客园博客，原文链接：http://www.cnblogs.com/firstyi/archive/2007/08/22/864942.html，如需转载请自行联系原作者