Hi @finchy70,
I'm not sure the way you've set up the database works very well - and it looks like you are making it complicated for yourself.
Would it not be a better idea to have a separate record for each job?
mon_job_number1_hours
mon_job_number2_hours
mon_job_number3_hours
Why not have 1 column for job_number and then another for hours
Doing it this way would allow you to make a query like:
/* Get total hours per job in Period 1 */
SELECT SUM(hours)
FROM your_database
WHERE period = 1
GROUP BY job_number
In eloquent it may look something like this:
App\Timesheet::groupBy('job_number')
->selectRaw('sum(hours)')
->where('period', '1')