how to weekdiff, monthdiff, yeardiff

should be like this?

SELECT TIMESTAMPDIFF(WEEK,now(),d), mod(TIMESTAMPDIFF(WEEK,now(),d), 10)
SELECT TIMESTAMPDIFF(MONTH,now(),d), mod(TIMESTAMPDIFF(MONTH,now(),d), 10)
SELECT TIMESTAMPDIFF(YEAR,now(),d), mod(TIMESTAMPDIFF(YEAR,now(),d), 10)

Hi there are some problems with the query

SELECT CASE WHEN RIGHT( RECUR, 1 ) =  'd'
THEN MOD( DATEDIFF( NOW( ) , DATETIMEDUE ) , SUBSTRING( RECUR, 1, LENGTH( RECUR ) -1 ) )
WHEN RIGHT( RECUR, 1 ) =  'w'
THEN MOD( TIMESTAMPDIFF( WEEK, NOW( ) , DATETIMEDUE ) , SUBSTRING( RECUR, 1, LENGTH( RECUR ) -1 ) )
WHEN RIGHT( RECUR, 1 ) =  'm'
THEN MOD( TIMESTAMPDIFF(MONTH , NOW( ) , DATETIMEDUE ) , SUBSTRING( RECUR, 1, LENGTH( RECUR ) -1 ) )
WHEN RIGHT( RECUR, 1 ) =  'y'
THEN MOD( TIMESTAMPDIFF( YEAR, NOW( ) , DATETIMEDUE ) , SUBSTRING( RECUR, 1, LENGTH( RECUR ) -1 ) )
END AS T, RECUR AS R, DATETIMEDUE

T      R      DATETIMEDUE      
0      1d      2015-01-19 20:40:59
0      1m      2015-01-19 23:59:59
1      2d      2015-01-18 20:48:59
1      2d      2015-01-18 06:00:59
-0      2m      2014-10-19 23:59:59 not correct
-0      2w      2015-01-05 03:10:59
-1      2w      2015-01-06 23:59:59
0      2y      2014-01-19 23:59:59 not correct
-0      2y      2013-01-18 20:40:59 not correct
0      3d      2015-01-16 22:38:59
-1      3m      2014-11-19 23:59:59 conflicts with below
-0      3m      2014-10-19 14:23:59
-2      3m      2014-11-19 20:44:59 conflicts
-2      4w      2014-11-10 20:49:59
-0      5w      2014-12-15 20:42:59
-4      5w      2014-12-16 23:59:59
0      8d      2015-01-11 20:39:59

First parameter of the Datediff function is the datepart that you want to be returned:
year  (yy, yyyy )
month  (mm, m)
week  (wk, ww)  

So you just need to change your query to return what you need. Example for month:

select d
, datediff(month, now(), d)
, mod(datediff(month,now(), d), 10) 
from test;

Select allOpen in new window

When you posted sample results and said that some were wrong, it would have helped if you said what you wanted to see instead.

 I don't have MySQL, so I can't test this, but I suspect that the time may be a factor.  For example, if DATETIMEDUE is 2014-10-19 23:59:59 and the current time is 2015-01-19 20:00:00, and you ask for the difference in months, the result may be 2, because it wouldn't be 3 full months until 2015-01-19 23:59:59.

 If you want to ignore the times and just look at the dates, I think you can use CURDATE() instead of NOW(), and use DATE on DATETIMEDUE, to extract the date without the time.

 You also need some kind of check to make sure that the basic interval has elapsed.  For example, if RECUR is 2y, but it hasn't even been 1 year yet, TIMESTAMPDIFF will give you 0 (years), so the MOD function will give you 0 (0 mod 2 = 0).

 But a more basic problem may be the "rounding" on the TIMESTAMPDIFF results.  For example:

-0      2y      2013-01-18 20:40:59 not correct

 I assume that you're saying that 0 is wrong because you ran that query on 01/19, so it had been 2 years and 1 day, not exactly 2 years.  But TIMESTAMPDIFF presumably produces integer results, so if you ask for the difference in years, any date from 01/18/2015 to 01/17/2016 will produce the same result -- 2 years.

 You could do a simple test by running a query like the following and checking the results:

SELECT TIMESTAMPDIFF(YEAR,'2013-01-18 20:40:59','2015-06-30 20:40:59');

 The difference is around 2 and a half years, but I'm guessing that the result will just be 2.

 James

Re: My last post, where I suggested using DATE_ADD

 FWIW, I realized later that I wasn't thinking of multiples of the interval.  For example, if the interval was 2y, I was just thinking of 2 years, not 4, 6, etc.  So that idea wasn't as straightforward as I thought it was.

 Hopefully Paul's code will give you what you need.


 Paul,

 When it's a year interval, shouldn't you also check the month, along with the day of the month?


 myyis,

 I kind of hate to even bring it up, because it could really complicate things, but there are potential problems because different months have a different numbers of days.  For a simple example, let's say that DATETIMEDUE was on 03/31 and the interval was 1 month.  There is no 04/31.  How would you want to handle that?

 Similarly, you have February and leap years.  What if DATETIMEDUE is on 02/29 and the interval is years?

 James

Hi James,
I can manipulate that kind of cases you've written, I see that Paul's code is ok. Thank you

>>"When it's a year interval, shouldn't you also check the month..."
good point, thanks

            WHEN RIGHT(RECUR, 1) = 'y' and @now > date(DATETIMEDUE) and month(@now) = month(DATETIMEDUE) and dayofmonth(@now) = dayofmonth(DATETIMEDUE)
                  THEN MOD(TIMESTAMPDIFF(YEAR, date(DATETIMEDUE), @NOW), SUBSTRING(RECUR, 1, LENGTH(RECUR) - 1))

I can manipulate that kind of cases you've written, I see that Paul's code is ok.

Glad to hear it.  Handling the different number of days per month seemed like something that could get really messy.

 James