How to find matching time intervals for more than 2 users

Question

Find best suitable time from given time interval of different users.

Rows: 5
fid  userid  FromDateTime           ToDateTime          flag
62   1   2012-07-18 01:         


        

Answer 1

I have found a hacky way to do this :

Perl has some thing called Set::IntSpan which has a intersect function(or method) that will find a range common to two intervals of numbers. The idea is to make use of it.

You can convert date time strings to timestamp(numbers) using strtotime("2012-08-27 02:02:02") in php. Once you have two pairs of timestamps, you can use the following sample perl code to find the intersection interval from which you can find the time.

use Set::IntSpan;

my $r1 = Set::IntSpan->new([ 5 .. 15 ]);
my $r2 = Set::IntSpan->new([ 2 .. 20 ]);

my $i = $r1->intersect($r2);

if ( !$i->empty and ( $i->max - $i->min ) >= 5 ) # criteria
{
print "hit\n"; # $i->max, $i->min are the timestamps you need
}
else
{
print "miss\n";
}

once you have the intersecting interval, you can get back the date time from timestamp (if you need) using date("Y-m-d H:i:s", $timestamp);

Here are some related links and references:

Calculate overlap between 2 ranges of numbers

Calling Perl script from PHP and passing in variables, while also using variablized perl script name

p.s. perhaps perl pros can wrap up the code into a function with 4 arguments? also, i understand this isn't the perfect answer to the question but imo the idea is cool.