mysql时间相减如何获取秒值

SELECT AcceptTime,CreateTime, (AcceptTime-CreateTime) sec FROM `req_dlr` WHERE SellOrg="CC经销商88" AND CreateTime>="1527350400" AND CreateTime <= "1529942399"
AND AcceptTime <>'0' AND makeid = '36000000' AND ReqState <> '97';

select time_to_sec('01:00:05'); -- 3605 转换为秒
select sec_to_time(3605); -- '01:00:05'

SELECT
sum(time_to_sec(M.A)- TIME_TO_SEC(M.C))
FROM
(
SELECT
date_fORMat(
FROM_UNIXTIME(AcceptTime),
'%H:%i:%S'
) A,
date_format(
FROM_UNIXTIME(CreateTime),
'%H:%i:%S'
) C
FROM
`req_dlr`
WHERE
CreateTime >= "1527350400"
AND CreateTime <= "1529942399"
AND AcceptTime <> '0'
AND makeid = '36000000'
AND ReqState <> '97'
) AS M
WHERE
M.A <= '19:00:00'
AND M.A >= '09:00:00';