Back in 2002, Jean-Luc Lachance gave a nifty algorithm (http://archives.postgresql.org/pgsql-sql/2002-06/msg00301.php) for determining the resulting date given a starting date and number of 'workdays' in the future. The trick was that weekends (Saturday and Sunday) could not be counted.
The algorithm looks like this:
date := now - day_of_the_week interval := interval + day_of_the_week date := date + int( interval/5)x7 + ( interval mod 5)
However, when I attempted to implement it, I found the answers I received to be problematic.
I'm sure the issue is in my interpretation of the algorithm, but I can't quite figure it out. Let's take an example. Starting on March 11, 2005, what date is 4 'workdays' in the future?
Step one:
date := now - day_of_the_week
March 5th = March 11th - 6 (6 is the day of week for Friday....march 11th).
...
What am I doing/interpreting wrong?
From the looks of it, variable date seems to calculate the first day of a week and for it to work day_of_the_week has to start from 0 so Sunday - 0, Friday - 5 (in US at least?)
Andre
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