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Editorial Team
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Asked: 2026-05-27T12:41:58+00:00

I have a table dutyrecord which stores multiple user working hours (subtotal) and a

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I have a table dutyrecord which stores multiple user working hours (subtotal)
and a UserID (volunteerID). With the following selecting statement I am about to set a total hours for each UserID:

SELECT
dutyrecord.VolunteerID,
SEC_TO_TIME( SUM( TIME_TO_SEC( SubTotal ) ) ) AS total
FROM
volunteerinfo
INNER JOIN
dutyrecord ON
( volunteerinfo.VolunteerID = dutyrecord.VolunteerID )
GROUP BY
dutyrecord.VolunteerID

Could I combine an update statement with a select to update total hours to each user? I tried something like and some other method with no luck:

UPDATE volunteerinfo 
SET 
TotalHours = 
( 
SELECT dutyrecord.VolunteerID , 
SEC_TO_TIME( SUM( TIME_TO_SEC( SubTotal ) ) ) AS total
FROM 
volunteerinfo
INNER JOIN 
dutyrecord ON ( volunteerinfo.VolunteerID = dutyrecord.VolunteerID )
GROUP BY 
dutyrecord.VolunteerID 
)
WHERE 
volunteerinfo.VolunteerID = dutyrecord.VolunteerID`

Can anyone give me a hand on this?

UPDATE
Sorry a few try and other examples I figure out the answer and a more clear way to ask my question.
To clear my question: Can I combine this process into one since I wants to make this process language independent? (I just carry 1 SQL statement in different perform.)

  • First, I select a table to give me the Sum of working hours for each person

    SELECT VolunteerID, SEC_TO_TIME( SUM( TIME_TO_SEC( SubTotal ) ) ) AS total
    FROM dutyrecord
    GROUP BY VolunteerID

    e.g. ID: 10001, 1:00:02 ID: 2001, 10:00:34 ….

  • After, I want to update the result (total) into another table according to their ID

    update Volunteerinfo
    set Volunteerinfo.totalhours = dutyrecord.total
    where Volunteerinfo.VolunteerID = dutyrecord.VolunteerID

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1 Answer

  1. Editorial Team

    My answer to this is to first join both tables together then the update and select statement will work in one row. please also comment me if inner join or other ways will increase the performance of this query.

    update volunteerinfo I 
 join
  (SELECT VolunteerID, SEC_TO_TIME( SUM( TIME_TO_SEC( SubTotal ) ) ) AS total
FROM dutyrecord
GROUP BY VolunteerID) R on R.volunteerid = I.volunteerid
set I.totalhours = R.total
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