mybatis long 类型返回为null报异常

 Mapper method 'com.mpn.dao.TWeatherMapper.avgWeatherTemperature attempted to return null from a method with a primitive return type (long).

  <select id="avgWeatherTemperature" resultType="java.lang.Long" parameterType="java.lang.String" >
        SELECT IFNULL(AVG(WeatherTemperature),0) AS OrderAverage FROM t_weather WHERE WeatherDate= #{date,jdbcType=VARCHAR};
  </select>
  
   <select id="sumWeatherRainfall" resultType="java.lang.Long" parameterType="java.lang.String" >
        SELECT SUM(WeatherTemperature) AS OrderAverage FROM t_weather WHERE WeatherDate= #{date,jdbcType=VARCHAR};
  
  </select>
  
   <select id="avghumidity" resultType="java.lang.Long" parameterType="java.lang.String" >
        SELECT IFNULL(AVG(WeatherHumidity),0) AS OrderAverage FROM t_weather WHERE WeatherDate= #{date,jdbcType=VARCHAR};
  </select>

由于返回为空long中没有此类型所以抛异常，改为

 <!-- 根据日期来进行计算平局值与 -->
   <select id="avgWeatherTemperature" resultType="java.lang.Long" parameterType="java.lang.String" >
        SELECT IFNULL(AVG(WeatherTemperature),0) AS OrderAverage FROM t_weather WHERE WeatherDate= #{date,jdbcType=VARCHAR};
  </select>
  
   <select id="sumWeatherRainfall" resultType="java.lang.Long" parameterType="java.lang.String" >
        SELECT IFNULL(SUM(WeatherTemperature),0) AS OrderAverage FROM t_weather WHERE WeatherDate= #{date,jdbcType=VARCHAR};
  
  </select>
  
   <select id="avghumidity" resultType="java.lang.Long" parameterType="java.lang.String" >
        SELECT IFNULL(AVG(WeatherHumidity),0) AS OrderAverage FROM t_weather WHERE WeatherDate= #{date,jdbcType=VARCHAR};
  </select>

用IFNULL来进行判断