Strange behavior of mysqli_query - php

Question

I ran into a problem with strange behavior of mysqli_query. There's a foreach-loop to update table rows but the update for the last loop doens't get written to the database (all the other updates get written successfully). There's no error and mysqli_affected_rows returns 1 as it should. The code pases through till the end, confirmed by an echo-statement after mysqli_query.
I tried to loop trough an array with only one element and the same problem.
What's going on here? Does anyone ran into the same problem?
OK...here's the significant part of the code, the whole code isn't possible cause there maximum 30000 characters allowed. I also echoed out the sql-string and everything is perfect. But as I said the update for the last loop (the last time when the loop is beeing executed) doesn't get written to the MySQL-DB.
$sql_getRelations = "SELECT id_machine, device_id, serial_number, variant_id, company_id, last_file FROM view_machines "
. "WHERE company_id NOT IN ('" . implode( '\',\'' , $btc_companies) . "') "
// . "AND id_machine = 158 "
. "AND device_type_id = 4 AND machine_status = 'active' "
. "ORDER BY id_machine ASC;";
$result_relations = mysqli_query($db_ed, $sql_getRelations);
$relations_arr = mysqli_fetch_all($result_relations, MYSQLI_ASSOC);
mysqli_free_result($result_relations);
foreach($relations_arr as $machine){
//...some other code here
$sql_update_device = "UPDATE device SET last_file = '" . $str_max_ts . "' WHERE id_device = " . $machine['device_id'] . ";";
$update_device = mysqli_query($db_ed, $sql_update_device);
if (!$update_device) {
error_log("\r\n" . date("Y-m-d H:i:s") . ': !!!!Updatefehler device: ' . $machine['device_id'] . ": " . mysqli_error($db_ed), 3, "C:/xampp/htdocs/cronjob/error_log.txt");
}
echo $machine['id_machine'] . ', ';
}
mysqli_close($db_ed);

Answer 1

I would perform debugging like the following to a text file. Wedge your data collection in the outer loops then rem that out and zero in on inner chunks. A divide and conquer strategy.
I would have tried to get my head into your email php but it is 675 lines of one foreach block :p
PHP:
<?php
//mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
mysqli_report(MYSQLI_REPORT_ALL);
error_reporting(E_ALL); // report all PHP errors.
ini_set("display_errors", 1);
echo "start<br/>";
// $file="/home/nate/debug123.txt";
$file="c:\\nate\\debug123.txt";
date_default_timezone_set('America/New_York');
$debugStr=date('Y-m-d H:i:s').": Start";
file_put_contents($file, $debugStr."\n", FILE_APPEND | LOCK_EX);
try {
$mysqli= new mysqli('localhost', 'theUser', 'thePassword', 'theDB_Name');
if ($mysqli->connect_error) {
die('Connect Error (' . $mysqli->connect_errno . ') '
. $mysqli->connect_error);
}
echo "I am connected and feel happy.<br/><br/>";
$query = "INSERT INTO `t921`(`thing`,`uniqueNum`,`views`) values ('aaa',577,0)"; // change that 577 each time else it fails unique
echo $query."<br>";
$mysqli->query($query);
$debugStr=date('Y-m-d H:i:s').": Affected rows: " .$mysqli->affected_rows.", Insert id: ".$mysqli->insert_id;
echo $debugStr."<br><br>";
file_put_contents($file, $debugStr."\n", FILE_APPEND | LOCK_EX);
$query = "UPDATE `t921` SET `views`=`views`+1 WHERE id=1";
echo $query."<br>";
$mysqli->query($query);
$id=1;
$debugStr=date('Y-m-d H:i:s').": UPDATE id=".$id.", Affected rows: " . $mysqli->affected_rows;
echo $debugStr."<br><br>";
file_put_contents($file, $debugStr."\n", FILE_APPEND | LOCK_EX);
$query = "UPDATE `t921` SET `views`=`views` WHERE id=1";
echo $query."<br>";
$mysqli->query($query);
$id=1;
$debugStr=date('Y-m-d H:i:s').": UPDATE id=".$id.", Affected rows: " . $mysqli->affected_rows;
echo $debugStr."<br><br>";
file_put_contents($file, $debugStr."\n", FILE_APPEND | LOCK_EX);
$mysqli->close();
} catch (mysqli_sql_exception $e) {
throw $e;
}
?>
Sample log file (debug123.txt):
2016-09-19 18:23:57: Start
2016-09-19 18:23:57: Affected rows: 1, Insert id: 27
2016-09-19 18:23:57: UPDATE id=1, Affected rows: 1
2016-09-19 18:23:57: UPDATE id=1, Affected rows: 0
Note the last update stmt was meant to change no data thus affected=0
Schema:
create table t921
( id int auto_increment primary key,
thing varchar(100) not null,
uniqueNum int not null,
views int not null,
unique key(uniqueNum)
);