在PHP中，MySQL尝试使用'$ mysqli-> multi_query'时抛出命令不同步错误

Question

In PHP, while I try to use $mysqli->multi_query second time, it throws me following error.

I looked at MySQL manual, and similar questions asked at SO, all suggest using either $mysqli->use_result(); or $mysqli->store_result(); or $mysqli->free_result();.

But none solves the problem. Any idea what I might be missing.

Current output - 'Commands out of sync; you can't run this command now'

<?php

$link = mysqli_connect('localhost', 'root', '', 'database');

$array1 = array(1 => 1000, 2 => 1564, 3 => 2646, 4 => 5462, 5 => 8974);
$array2 = array(23 => 1975, 24 => 3789, 25 => 4658, 26 => 5978, 27 => 6879);

$update1 = '';
foreach($array1 as $k => $v) {
    $update1 .= "UPDATE `ps_temp` SET `price` = {$v} WHERE `id` = {$k};";
}

$res = mysqli_multi_query($link, $update1);     // Table is updated
$error = mysqli_error($link);
echo 'Error 1 - '.$error.'<hr>';                // Output : Error 1 - 

$update2 = '';
foreach($array2 as $k => $v) {
    $update2 .= "UPDATE `ps_temp2` SET `price` = {$v} WHERE `id` = {$k};";
}

mysqli_multi_query($link, $update2);            // Table is not updated.
$error = mysqli_error($link);
echo 'Error 2 - '.$error.'<hr>';                // Output: Error 2 - 'Commands out of sync; you can't run this command now'

?>

Answer 1

You have to fetch all results - for example:

// here: first multi query

// fetch all results
while( mysqli_more_results($link) ){
    $result = mysqli_store_result($link);
    mysqli_next_result($link);
}

// here: second multi query

Some SQL systems in some languages are "lazy". They send query only when you ask for results (for example LINQ in C#). Maybe PHP do the same. It blocks connection waiting for your result fetching.