Calculating + Adding Times

[[FG]Omega]

Ok, I don't know if the title is correct, but I'll give it a try.

I have 2 questions:
I have stored 2 Dates in one row in one table. For instance:
+-------+--------+
| 12:00 | 13:15 |
+-------+--------+

Now I want to calculate the difference between these two times. In the example above the difference would be 1 hour and 15 Minutes. I want it to display like "1,25". How do I calculate this? If I have (e.g) 20 rows and I want to calculate and display 20 differences.

My second question is: How do I calculate the 20 differences? Like this:
1,25 ; 2,30, 1,45; 7,15; and so on. And I want the sum of all the 20 differences. I hope you understand what I mean.
Like 1.25 + 2.30 + 1.45 + 7.15 etc.

I'd appreciate any help.

[Lats]

I don't understand the '20 differences' bit, so I'll skip it.

For the first, you can do something like this...

$result = mysql_fetch_array(mysql_query($sql));
$start = strtotime($result['start_bit']);
$end = strtotime($result['end_bit']);
$diff = ($end - $start) / 60 / 60;
echo "Difference ".number_format($diff,2)." <br>"; 

[[FG]Omega]

doesn't work :/
The "Time1" and "Time2" in the DB are like 00:00:00 (MySQL-Type: TIME)

*edit*: Figured out why it didn't work. Thank you

[[FG]Omega]

No one can help me with adding all the timediffs?

I mean, when I have calculated all the timediffs, which are stored in the DB, I want the sum of all timediffs displayed in the bottom.
Like:

+--------------------------+
| Time 1 | Time 2 | Timediff |
+--------------------------+
| 12:00 | 13:00 | 1, 00 |
+------------------------- +
| 15:00 | 16:00 | 1,00 |
+--------------------------+
SUM: 2,00

^--like this above. Ok, In the example 2 variables aren't that much, so I can write $sum = $time1 + $time2 - but when I have more than 50 times stored in the DB...

So, anyone can help?

[Lats]

Something like this...

$sql_result = mysql_query($sql);
while($result = mysql_fetch_array($sql_result))
{
 $start = strtotime($result['start_bit']);
 $end = strtotime($result['end_bit']);
 echo "$start - $end - ";
 $diff = ($end - $start) / 60 / 60;
 echo "Difference ".number_format($diff,2)." <br>";
 $total_diff += $diff;
}
echo "Total ".number_format($total_diff,2); 

[[FG]Omega]

Thanks, dude, works excellent