Hi, to be honest I’m not sure if it actually is a bug, but this function does not follow the ISO standard of numbering weeks.
For example, today (2016-10-13) should be week 41, but the function returns 42. Probably because the first week of this year was week 53 according to the international standards.
Never mind: I just found that DATETIME_FORMAT(NOW(), ‘W’) does return the ISO week number.
A reference in the formula editor (for WEEKNUM) would be helpful. 
That’s great, the only problem is that when using DATETIME_FORMAT, Monday is the first the of the week, but I just figured out a way to solve this (ie to make Sunday the first day AND use ISO week numbers), by adding +1 days like that:
VALUE(DATETIME_FORMAT(DATEADD(Date,1,"days"),"W"))
Note I used VALUE() to convert the week number into an actual number, not string
Hope this helps others too !
That’s great, the only problem is that when using DATETIME_FORMAT, Monday is the first the of the week, but I just figured out a way to solve this (ie to make Sunday the first day AND use ISO week numbers), by adding +1 days like that:
VALUE(DATETIME_FORMAT(DATEADD(Date,1,"days"),"W"))
Note I used VALUE() to convert the week number into an actual number, not string
Hope this helps others too !
QQ here, when I use the above it still put 12/29-12/31 as 2024-01. is 2024-53 not possible?
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