当行包含isnull时使用datediff和sum

Question

我需要在MySQL中进行以下计算

IFNULL(c.ACTUAL_END_DATE, CURDATE()) AS ACTUAL_END_DATE

目前，我有两个日期时间字段，我想做日期，并找到补偿＆＃34;为空的总天数＆＃34;正如我已经做的那样

我想总结一下

SELECT 
    a.PERSONNEL_ID,
    a.LAST_NAME,
    a.FIRST_NAME,
    b.NUM,
    c.ACTUAL_START_DATE,
    c.payroll_job_id,
    IFNULL(c.ACTUAL_END_DATE, CURDATE()) AS ACTUAL_END_DATE
FROM
    personnel a,
    num b,
    personnel_service c
WHERE
    a.CURRENTLY_SERVING_SHIP_ID = b.ship_id
        AND a.current_status_lookupitem = 10142
        AND a.personnel_id = c.personnel_id
        AND c.payroll_job_id IN ('1')
        AND c.SERVICE_TYPE_LOOKUPITEM = 10161 
        AND c.ACTUAL_START_DATE is not null