Re: [sqlite] Calculate years and months difference with Julian Date?

[John Stanton]

I answered your question.  It is possible and showed you how to do it. 
The rest is up to you.

RB Smissaert wrote:
I am not into C and I want to stay clear from compiling SQLite.
Or do I misunderstand this?
RBS

-----Original Message-----
From: John Stanton [mailto:[EMAIL PROTECTED] 
Sent: 17 December 2006 20:38
To: sqlite-users@sqlite.org
Subject: Re: [sqlite] Calculate years and months difference with Julian
Date?

Have a look at Sqlite date code.  I just lifted its data structures and 
used its functions to build user functions to give month etc.  The 
algorithms are accurate and they are easy to use.  I found setting up 
user functions to do those calculations made the SQL simpler.

The functions are in a file called date.c.  Here is one function which 
we added to Sqlite to get the month number as an example -

*!!!TSI addition.*/
/*-- monthFunc ---------------------------------------------
Return the month number.  Added by TSI.*/
static void monthFunc(sqlite3_context *context, int argc,
   sqlite3_value **argv){

   DateTime x;

   if (isDate(argc, argv, &x) == 0){
     computeYMD(&x);
     sqlite3_result_int(context, x.M);
   }  /*if*/
}    /*monthFunc*/
/*!!!End TSI addition.*/

RB Smissaert wrote:

Is it possible with Julian dates in 2 fields to calculate the months

and/or

years difference between those 2 dates?

I know I can subtract the 2 dates and divide by 30 (or 30.42) or 365 and
take it from there, but I would like it a bit more precise, so for

example:

Is 2 March 2006 more than one month after 1 February 2006?
If calculated with a simple division the answer would be no, but I would
like it to be yes.

Had a look at the date/time functions on the WIKI site, but couldn't see

it.

RBS






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