Mybatis使用distinct问题及处理

 <resultMap id="versioncodeResult" type="java.lang.String" >
    <result column="code" property="code" jdbcType="VARCHAR" />
  </resultMap>
  
<select id="selectVersionCodeByParam" parameterType="com.entity.OdpsrequesttoidbtableParam" resultMap="versioncodeResult">
    <!--
      WARNING - @mbg.generated
      This element is automatically generated by MyBatis Generator, do not modify.
    -->
    select
    <if test="distinct">
      distinct
    </if>
    versioncode as code
    <include refid="Base_Column_List" />
    from odpsrequesttoidbtable
    <if test="_parameter != null">
      <include refid="Param_Where_Clause" />
    </if>
    <if test="orderByClause != null">
      order by ${orderByClause}
    </if>
    <if test="page">
      limit #{pageIndex},#{pageSize}
    </if>
  </select>

###
 SQL: select             distinct           versioncode as code    
 id, gmt_create, gmt_modified, apiname, pkey, versioncode, appkey      
 from odpsrequesttoidbtable                         WHERE (  appkey = ? )

<select id="selectVersionCodeByParam" parameterType="com.entity.OdpsrequesttoidbtableParam" resultMap="versioncodeResult">
    <!--
      WARNING - @mbg.generated
      This element is automatically generated by MyBatis Generator, do not modify.
    -->
    select
    <if test="distinct">
      distinct
    </if>
    versioncode as code
    from odpsrequesttoidbtable
    <if test="_parameter != null">
      <include refid="Param_Where_Clause" />
    </if>
    <if test="orderByClause != null">
      order by ${orderByClause}
    </if>
    <if test="page">
      limit #{pageIndex},#{pageSize}
    </if>
  </select>