mysql 查询 两个表中不同字段的 和，并通过两个表的时间来分组

( SELECT
sum( a.cost_sum ) AS sum_cost,
sum( a.phone_sum ) AS sum_phone,
sum( a.arrive_sum ) AS sum_arrive,
FORMAT( sum( a.cost_sum ) / sum( a.arrive_sum ), 0 ) AS arrive_cb,
a.time AS time 
FROM
    (
        SELECT
            FROM_UNIXTIME( time, "%Y-%m-%d" ) AS time,
            sum( cost ) AS cost_sum,
            sum( arrive_true ) AS arrive_sum,
            sum( phone ) AS phone_sum 
        FROM
            `cmf_test_jj_data` 
        GROUP BY
            `time` UNION
            (
        SELECT
            FROM_UNIXTIME( time, "%Y-%m-%d" ) AS time,
            0 AS cost_sum,
            sum( arrive_num ) AS arrive_sum,
            0 AS phone_sum 
        FROM
            cmf_test_jj_arrive_new 
        GROUP BY
            time 
            ) 
    ) a 
WHERE
    ( `a`.`time` >= 0 AND `a`.`time` <= 1551801600 ) 
GROUP BY
    a.time 
ORDER BY
    a.time DESC 
    )