[UPHPU] mysql date calculation bug

[Jim Anderson]

Jennifer Charrey wrote:
> Why not just use a certain number of days instead of months as your 
> intervals. Sure, some months are different lengths, but assuming 30 
> days  in a month should be fine for these purposes. So instead of 
> going 6 months back, where multiple starting dates might resolve to 
> the same end date (like in the case of Sept. 28-31), just do 180 days 
> back and you'll always get the same day. Same for your other 
> intervals. Wouldn't that be a little simpler than trying to figure out 
> if you already sent something in the last 5 days?
unfortunately, that is not an option. these are contract based and the 
contract verbiage is in months not days. believe me, i would much prefer 
the method you described. :) in fact, i fought for it, and lost. :(


thnx though. i like the simplicity of that approach much better.

-jim

>
> Jennifer
>
>
>
> Jim Anderson wrote:
>> initial looks tells me that the following won't work either. run the 
>> following:
>>
>> SELECT DATE_ADD('2007-02-28', INTERVAL 6 MONTH) + INTERVAL 49 DAY = 
>> CURDATE();
>> SELECT DATE_ADD('2007-03-01', INTERVAL 6 MONTH) + INTERVAL 45 DAY = 
>> CURDATE();
>>
>> those 2 queries both return true. notice, though, that they are 1 
>> calendar day apart and 4 interval days apart. this is going to have 
>> the same basic effect as before. :(
>>
>> i think the least development time is going to run a check to see if 
>> the email has been sent within 5 days and , if so, don't send it 
>> again. [5 days chosen as the largest margin of duplication, that i 
>> can see, is 4 days [february] but this would happen in any month 
>> begin/end cycle.]
>>
>> i do like the brain storming though. feel free to keep up the ideas!
>>
>> thnx,
>> -ja
>>
>>
>>
>> Ben Reece wrote:
>>> Jim Anderson wrote:
>>>> A good suggestion. I thought of that as well, but seem to remember 
>>>> coming across similar issues. I've had about 15 things in my head 
>>>> throughout the day so I may be getting some of my issues/projects 
>>>> schmeared though. Do you think doing it that way would skip over 
>>>> anyone? I saw that as an unlikely, but possible, concern.
>>>>
>>>> i was thinking something like:
>>>>
>>>> WHERE DATE_ADD(start_date, INTERVAL 6 MONTH) + INTERVAL 45 DAY = 
>>>> CURDATE()
>>>>
>>>> but i haven't had the time to test it out.
>>>>
>>>> to fill out the scenario a bit fuller, the criteria is this:
>>>>
>>>> * 9 different emails. one for each of the following date scenarios.
>>>> * six months after sign-up minus 45 days
>>>> * six months after sign-up minus 30 days
>>>> * six months after sign-up minus 15 days
>>>> * six months after sign-up minus 5 days
>>>> * six months after sign-up [minus 0 days]
>>>> * six months after sign-up plus 15 days
>>>> * six months after sign-up plus 30 days
>>>> * six months after sign-up plus 45 days
>>>> * six months after sign-up plus 60 days
>>>>
>>>> That is the schedule that i have in place.
>>>>
>>>> -jim
>>> I don't see any problem with that statement -- seems like it would 
>>> work without any problems.  The only possible issue would be that 
>>> the emails might not be the exact number of days apart that you 
>>> show, since you're adding months, and the date can move a little bit 
>>> because of that.
>>> Ben
>>
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