I want to update the one column in database on click the vote button

Question

I started writing code for a basic voting system. But I got this error message.

Warning: mysqli_query() expects parameter 1 to be mysqli, bool given in E:\My-WORLD\xampp\htdocs\php-tut\voting\vote.des.php on line 6

<?php
  $con = mysqli_connect("localhost","root","","voting") || die("not 
 connected");
echo "connected";

if(isset($_POST['ele'])){

   global $con;

   $vote_ele = "update votes set ele = ele + 1";
   $run = mysqli_query($con,$vote_ele);

   if($run){
      echo "voted to electronics";
   }
   else{
      echo mysqli_error($run);
   }

  }
 ?>

Your Common Sense · Answer 1 · 2019-07-07T08:25:21.280

Neither || or or should be ever written in connection to any mysqli function.

How to properly connect with mysqli:

$host = '127.0.0.1';
$db   = 'voting';
$user = 'root';
$pass = '';
$charset = 'utf8mb4';

mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
try {
    $con = mysqli_connect($host, $user, $pass, $db);
    mysqli_set_charset($con, $charset);
} catch (\mysqli_sql_exception $e) {
     throw new \mysqli_sql_exception($e->getMessage(), $e->getCode());
}

Given this script is not the only one uses a mysql connection, store this code in a separate file named mysqli.php and then include it in other files. Therefore your current code will become

<?php
include 'mysqli.php';
if(isset($_POST['ele']))
{
   $vote_ele = "update votes set ele = ele + 1";
   $run = mysqli_query($con,$vote_ele);
   echo "voted to electronics";
}

See - it is concise, tidy and reusable.

score -2 · Answer 2 · answered Jul 07 '19 at 07:31

-2

When you use $con = mysqli_connect("localhost","root","","voting") || die("not connected"); you are assigning a bool to $con variable. So it is not mysqli anymore.

Also, When you use global $con you are overriding $con value, So it is not mysqli which you assigned in the pervious line anymore.

try this:

        $con = mysqli_connect("localhost", "root", "", "voting");

        if (mysqli_connect_errno())
            die("Failed to connect to MySQL: " . mysqli_connect_error());

        echo "connected";

        if (isset($_POST['ele'])) {

            // This will override $con value!!
            // global $con;

            $vote_ele = "update votes set ele = ele + 1";
            $run = mysqli_query($con, $vote_ele);

            if ($run) {
                echo "voted to electronics";
            }
            else {
                echo mysqli_error($run);
            }

        }

answered Jul 07 '19 at 07:31

Hamed Ghasempour

435
3
12

your second statement is wrong. global $con is pointless but harmless – Your Common Sense Jul 07 '19 at 07:37
also, https://stackoverflow.com/questions/15318368/mysqli-or-die-does-it-have-to-die – Your Common Sense Jul 07 '19 at 07:39
That's not my statement. Consider that I commented. About die(), that's post owner statement, not mine. I just updated the owners' code. – Hamed Ghasempour Jul 07 '19 at 07:43
"When you use global $con you are overriding $con value" is the second statement you made in your answer. – Your Common Sense Jul 07 '19 at 07:45
Man! I'm just trying to say what is happening! That's not mine again! I commented that in my sample. – Hamed Ghasempour Jul 07 '19 at 07:46
Yes. and you are wrong on this account. Please pay some heed to my words before commenting back. Thank you. – Your Common Sense Jul 07 '19 at 07:47

I want to update the one column in database on click the vote button

2 Answers2