时间：2021-11-24 13:58:46 | 栏目：JAVA代码 | 点击：次
<resultMap id="ResultOfLong" type="java.lang.Long">
<result column="budget" property="budget" javaType="long"/>
</resultMap>
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！