Mybatis中如何使用sum对字段求和

  <select id="gettotalincome" resulttype="com.lws.test.modules.user.entity.userincomeentity">
    select sum(income) as totalincome
    from income_log
    where uid = #{uid,jdbctype=bigint}
 </select>

public class userincomeentity {
    private bigdecimal totalincome;
}

<select id="getordersummoneybyusercode" parametertype="string" resulttype="bigdecimal">
selec sum(order_money ) from gm_order where add_uid = #{usercode}
</select>

<select id="getordersummoneybyusercode" parametertype="string" resulttype="bigdecimal">
select coalesce(sum(order_money),0) from gm_order where add_uid = #{usercode}
</select>