子查询返回多条报错误

UPDATE `0220数据统计` AS a
SET a.`T+7复购金额` = (
    SELECT
        ROUND(SUM(b.real_pay) / 10000, 2) AS 累计消费金额
    FROM
        arm_changsha.goods_sales AS b
    LEFT JOIN arm_changsha.ms_member_def AS c ON c.id = b.member_id
    WHERE
        c.mobile = a.`手机号码`
    AND b.create_date >= '2019-01-14 00:00:00'
    AND b.create_date <= '2019-01-27 23:59:59'
    AND b.sales_type = '1'
    GROUP BY
        b.member_id
);

 

报错误，返回子查询返回多条。  注释掉就可以。数据问题。

    GROUP BY
        b.member_id