Need help in storing Tariff values

I am working on a application which has an option to set the time based tariff for the usage. The time interval is 15 mins. So the there will be 96 [24*4] values for a given day

[00:00 to 00:15, 00:15 to 00:30, 00:30 to 00:45, 00:45 to 01:00 ....... 23:45 to 00:00]

As of now I'm storing these values as

{"00:00 - 01:00":"2","00:00 - 00:15":"0.00","00:15 - 00:30":"0.00","00:30 - 00:45":"0.00","00:45 - 01:00":"0.00", , , , , , , , ,"23:45 - 00:00":"0.00"}

But finding it difficult while generating the report :-\.  In report I have to check the usage time falls in which time interval and apply the rate defined for that interval.

Help needed urgently...

Sorry forgot to mention. I am using PHP and MySQL on Linux to develop this application.

The code you put up as how your storing it looks like JSON as apposed to a PHP array. It may be easier to store them in the following manner:

$startEndTime = "45"; //Seconds
$rateToUse = array(); // This is an array as 45 sec can fall into 0-60, 30-45

$times["0-60"]["Rate"]=2;
$times["0-15"]["Rate"]=0;
$times["15-30"]["Rate"]=0;
$times["30-45"]["Rate"]=0;

foreach($times as $interval=>$rate) {
     $startEndTime = split($interval,'-');
     if($timeTocheck >= $startEndTime[0] && $timeToCheck <= $startEndTime[1]) {
          $ratesToUse[] = $rate["Rate"];
     }
}

Thanks for the replay.

Yes I'm using the JSON to store the values.

I can't use the following code.

$times["0-60"]["Rate"]=2;

$times["0-15"]["Rate"]=0;

$times["15-30"]["Rate"]=0;

$times["30-45"]["Rate"]=0;

Because I have to use the hour along with the minutes. [ Tariff rate for 00:00 - 00:15 may be different from 01:00 - 01:15. ]

I would store the intervals as:

id | start | rate

Where "start" is the first second of the interval.  Each interval is therefore 900 seconds long and they are as following:

0 - 899        00:00 to 00:14:59

900 - 1799        00:15 to 00:29:59

1800 - 2699      00:30 to 00:44:59

Then you can load an array of "start" => "rate"

<?php
// Note that you'll have to use appropriate database functions
$rates = array();
$q = query( "select start, rate from the_table order by start" );
while( $r = fetch_object( $q ) ) {
    $rates[ $r->start ] = $r->rate;
}
?>

Now to determine the tax rate for a given timestamp:

<?php
// some datetime
$dt = '2010-09-01 16:23:42';
// convert to timestamp
$ts = strtotime( $dt );
// determine seconds of day
$seconds = 3600 * ((int)date( 'H', $ts )) + 60 * ((int)date( 'i', $ts )) + ((int)date( 's' ));
// now determine which interval it starts in
$interval = $seconds - ($seconds % 900);
// look up
echo 'rate is: ' . $rates[ $interval ];
?>

That's not thoroughly thought through but it might get you there.

Hi roopurt18,

Thanks a lot. It worked very well. 

Glad to hear it.  Also keep in mind that when working with financial data it's a good idea to use the arbitrary precision math libraries.