Mybatis的association使用子查询结果错误的问题解决

<?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="com.li.application.mapper.LgsProfitForecastMapper">


    <resultMap type="LgsProfitForecast" id="LgsProfitForecastResult">
        <association property="predictionCompletionDateStr" select="selectPredictionCompletionDateStr" 
                     column="type" javaType="string"/>
    </resultMap>

    <select id="selectProfitForecastList"  resultMap="LgsProfitForecastResult">
        SELECT
            *
        FROM
            lgs_profit_forecast
    </select>


    <select id="selectPredictionCompletionDateStr" resultType="string">
        select
            GROUP_CONCAT(prediction_completion_date)
        from
            ( select prediction_completion_date from lgs_profit_forecast  where type = #{type}  limit 4)	a
    </select>
</mapper>

   <resultMap type="LgsProfitForecast" id="LgsProfitForecastResult">
        <result property="type" column="type"/>
        <association property="predictionCompletionDateStr" select="selectPredictionCompletionDateStr" 
                     column="type" javaType="string"/>
    </resultMap>