Mapper method 'com.autoyol.mapper.trans.AccountLogMapper.getTotalIncomByMemNoLastest attempted to return null from a method with a primitive return type (int).解决方法

1.打开日志输出，降低日志级别。

<AppenderRef ref="console" level="trace"></AppenderRef>  否则看不到报错。。

2.调整mysql语句，不能使用order by limit之类的

<!-- SELECT IFNULL(amt,1) FROM account_log WHERE mem_no=#{value} AND income_type != 4 ORDER BY id DESC LIMIT 1 -->
    <select id="getTotalIncomByMemNoLastest" parameterType="int" resultType="Integer">

        SELECT IFNULL(MAX(amt),1) FROM account_log WHERE id = (SELECT MAX(id) FROM account_log WHERE mem_no=#{value} AND income_type != 4)
    </select>

<!--
    处理非空的情况，同时处理MAX(order_no)订单号的情况。
    SELECT order_no AS orderNo FROM trans WHERE invite_group = #{groupOrderNo} AND is_group=1 AND order_no != #{orderNo} AND STATUS = 21 ORDER BY id ASC LIMIT 1
    -->
    <select id="getTransGroupOrderRestToIsGroup" resultType="java.lang.Long">
        SELECT IFNULL(MAX(order_no),0) AS orderNo FROM trans WHERE id = (
            SELECT IFNULL(MIN(id),0) AS orderNo FROM trans WHERE invite_group=#{groupOrderNo} AND is_group=1 AND order_no != #{orderNo} AND STATUS = 21
        )
    </select>