PHP mySQL Time Between Rows - php

Question

Hello I am stuck on this. Looking to be able to pull the time between 2 start/stop rows from a mySQL database. My table looks like this
fillercdown_ndx | time | B3_4_5
1 | 2016-06-16 14:59:45 | 0
2 | 2016-06-16 15:03:11 | 1
Basically when its recorded as 0 the machine stopped and when the record is 1 the machine restarted. I need to be able to calculate the amount of time the machine was down between certain times like 8AM-5PM. Was going to use PHP to display it upon users time entered, but have no idea on the SQL command.
Anyone know the best way to be able to find this?
Create table
CREATE TABLE `fillercdown` (
`fillercdown_ndx` int(11) NOT NULL AUTO_INCREMENT,
`time` datetime DEFAULT NULL,
`B3_4_5` int(11) DEFAULT NULL,
PRIMARY KEY (`fillercdown_ndx`),
KEY `fillercdowntimendx` (`time`)
) ENGINE=InnoDB AUTO_INCREMENT=7 DEFAULT CHARSET=latin1
UPDATE:
There will be hundreds of these "start" and "stop" entries. My end all goal would be in php to give the user a small form asking them to provide a time range like 8AM-5PM and then be able to calculate all the time where the machine was "stopped" (which is when B3_4_5 is at 0). I just can't seem to figure out the right SQL call to get the time differences between each 0 and 1 and add them together between a set time range

Answer 1

This is what I am currently using to do the same thing it sounds like you're trying to do. I'm using PDO but this could be adapted fairly easily for mysqli if you need to use that. This depends on alternating off/on values by time. If there are any consecutive off or on rows for whatever reason, the expected result becomes ambiguous.
// First select everything in the requested range ordered by time.
$sql = "SELECT `time`, B3_4_5 FROM your_table WHERE `time` BETWEEN ? AND ? ORDER BY `time`";
$stmt = $pdo->prepare($sql);
$stmt->execute([$query_start, $query_end]);
// Initialize two DateTime objects (start and end) used to calculate the total time.
$total_start = new DateTime('00:00');
$total_end = clone $total_start;
$off = null;
while ($row = $stmt->fetchObject()) {
if ($row->B3_4_5) {
$on = new DateTime($row->time);
// increment total end time with difference between current off/on times
if ($off) {
$total_end->add($on->diff($off));
}
} else {
$off = new DateTime($row->time);
}
}
// total downtime is difference between start and end DateTimes
$total_downtime = $total_start->diff($total_end);
$total_downtime is a DateInterval object. You can get return a message using its format method:
echo $total_downtime->format('Total downtime: %h hours, %i minutes, %s seconds.');

Answer 2

This is the basic idea... It selects the result into a single row andcolumn, which you can then fetch withPHP`...
This solution assumes that stops & starts come in pairs, i.e: the ID of a start will be +1 that of a stop. Otherwise you should SELECT/JOIN the ID that is > that of the stopped one, and LIMIT it to 1.
A self join might not yield optimal performance wise, so be careful and measure execution times with some data to be on the safe side.
http://sqlfiddle.com/#!9/de72bf/1
CREATE TABLE fillercdown (
`fillercdown_ndx` int(11) NOT NULL AUTO_INCREMENT,
`time` datetime DEFAULT NULL,
`B3_4_5` int(11) DEFAULT NULL,
PRIMARY KEY (`fillercdown_ndx`),
KEY `fillercdowntimendx` (`time`)
) ENGINE=InnoDB AUTO_INCREMENT=0 DEFAULT CHARSET=latin1;
INSERT INTO fillercdown
(`time`, `B3_4_5`)
VALUES
('2016-06-16 14:00:45', 0),
('2016-06-16 14:01:00', 1),
('2016-06-16 16:00:00', 0),
('2016-06-16 16:01:00', 1)
;
SELECT SUM(TIMEDIFF(g.`time`, f.`time`))
FROM fillercdown f
INNER JOIN fillercdown g
ON g.`fillercdown_ndx` = (f.`fillercdown_ndx` + 1)
AND g.`B3_4_5` = 1
AND TIME(g.`time`) BETWEEN '08:00:00' AND '17:00:00'
WHERE f.`B3_4_5` = 0
AND TIME(f.`time`) BETWEEN '08:00:00' AND '17:00:00'
If you want to include times where the machine stopped but has not yet restarted, you can do something like this:
http://sqlfiddle.com/#!9/d113b9/9
INSERT INTO fillercdown
(`time`, `B3_4_5`)
VALUES
('2016-06-16 14:00:45', 0),
('2016-06-16 14:01:00', 1),
('2016-06-16 16:00:00', 0),
('2016-06-16 16:01:00', 1),
('2016-06-16 16:02:00', 0)
;
SELECT SUM(TIMEDIFF(COALESCE(g.`time`, '2016-06-16 16:02:01'), f.`time`))
FROM fillercdown f
LEFT JOIN fillercdown g
ON g.`fillercdown_ndx` = (f.`fillercdown_ndx` + 1)
AND g.`B3_4_5` = 1
AND TIME(g.`time`) BETWEEN '08:00:00' AND '17:00:00'
WHERE TIME(f.`time`) BETWEEN '08:00:00' AND '17:00:00' AND f.`B3_4_5` = 0
You could replace 2016-06-16 16:02:01 with NOW() or something based on f.time, it depends on your application needs of course.
If you never want to get NULL but rather 0, if there are no matching rows, then do something like: COALESCE(SUM(...), 0).
If you prefer a scripted solution you can always do something like this:
SELECT f.`time`, f.`B3_4_5`
FROM fillercdown f
WHERE TIME(f.`time`) BETWEEN '08:00:00' AND '17:00:00'
And then compute the sum, like so (psuedocode):
stopped = null;
pairs = []
for ( row in rows )
if ( row.isStopped ) stopped = row
else
pairs += [stopped, row]
stopped = null
sum = 0
for ( pair in pairs )
sum += duration( pair[0], pair[1] )