PHP Warning: mysqli::query(): Couldn't fetch mysqli

Question 1

Here's my current code:

<?php 
$key = $_REQUEST['key'];
$url = $_REQUEST['url'];

include_once '../../dbconnect.php';

$query = $conn->query("SELECT * FROM members WHERE apikey='$key' && status='Active'");
$userRow=$query->fetch_array();
$conn->close();

/// Verify the URL starts with http:// or https://
if (0 === strpos($url, 'http://') || 0 === strpos($url, 'https://')) {
$url = $url;
} else {
$url = "http://$url";
}

/// Verify the key is 32 characters
if (!preg_match('/[^A-Za-z0-9]/', $key) && (strlen($key) == 32)) {

/// Verify the URL isn't malicious
if (filter_var($url, FILTER_VALIDATE_URL) === FALSE) {
    die('Error:  Invalid URL');
} else {

if ($userRow['status'] === 'Active') {

function generateRandomString($length = 8) {
    $characters = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
    $charactersLength = strlen($characters);
    $randomString = '';
    for ($i = 0; $i < $length; $i++) {
        $randomString .= $characters[rand(0, $charactersLength - 1)];
    }
    return $randomString;
}

$redirect = generateRandomString();

$addshort = $conn->query("INSERT INTO short_".$redirect[0]." (redirect, apikey, url) VALUES ('".$redirect."','".$key."','".$url."')");

if ($conn->query($addshort) === TRUE) {
echo "added correctly";
} else {
echo "there was an error";
}

$conn->close();

} else {
echo "Error:  Account Not Active";
}

}

} else {
die('Error:  Invalid API Key');
}
?>

Here's the error_log:

[18-Oct-2016 12:21:31 America/New_York] PHP Warning:  mysqli::query(): Couldn't fetch mysqli in /home/username/public_html/subdomains/url/index.php on line 40
[18-Oct-2016 12:21:31 America/New_York] PHP Warning:  mysqli::query(): Empty query in /home/username/public_html/subdomains/url/index.php on line 42
[18-Oct-2016 12:21:31 America/New_York] PHP Warning:  mysqli::close(): Couldn't fetch mysqli in /home/username/public_html/subdomains/url/index.php on line 48

You can see on the 7th line where I connect to the database for the first time:

$query = $conn->query("SELECT * FROM members WHERE apikey='$key' && status='Active'");

And that line is working. However, the second time I'm connecting to do an INSERT, I'm getting the above errors:

$addshort = $conn->query("INSERT INTO short_".$redirect[0]." (redirect, apikey, url) VALUES ('".$redirect."','".$key."','".$url."')");

Is there something I'm missing from just staring at this code for too long?

Question 2

Your connection has been closed, after execution of first SELECT Statement, it means connection closed to early:

$conn->close();

You need to use close() after your all queries or re build connection. ist one is the better option.

You are getting user input $_REQUEST['key'], it means your query is open for SQL injection, this will help you to understand how can you prevent your code with SQL injection: How can I prevent SQL injection in PHP?

Question 3

Probably somewhere you have DBconnection->close(); and then some queries try to execute .

Hint: It's sometimes mistake to insert ...->close(); in __destruct() (because __destruct is event, after which there will be a need for execution of queries)

Question 4

I solved the issue!

I placed my variables into crontab -e file before cron jobs but without export command.

DB_SERVER='*here db credential*'
DB_USER='*here db credential*'
DB_PASS='*here db credential*'
DB_NAME='*here db credential*'

It makes the variables accessible for all cron jobs.

So when I am using cron jobs it works just fine!

Question 5

<?php
$sql = new mysqli('127.0.0.1','root','Qwert12345','plot_io_db');
//echo $sql->query('Select * From players');
?>

It will work. Just remove port from localhost (127.0.0.1)

Question 6

mysqli_connect("","username" ,"password","databasename");//Server name cannot be NULL

use loaclhost for server name(In Loacl)

<?php
    $con = mysqli_connect("localhost","username" ,"password","databasename");

    if (mysqli_connect_errno())
    {
        echo "Failed to connect to MySQL: " . mysqli_connect_error();
    }
?>

Or can use MySQLi Procedural

<?php
    $servername = "localhost";
    $username = "username";
    $password = "password";

    // Create connection
    $con = mysqli_connect($servername, $username, $password);

    // Check connection
    if (!$con) {
        die("Connection failed: " . mysqli_connect_error());
    }
    echo "Connected successfully";
?>

EDIT 01

$servername = "localhost";
$username = "root";
$password = "";

PHP Warning: mysqli::query(): Couldn't fetch mysqli

Answers

php,mysql,mysqli