What Does the MySQLi_Error() Expects Parameter 1 to Be MySQLi, Null Given Mean

What does the mysqli_error() expects parameter 1 to be mysqli, null given mean?

You need to define: $dbc before

 $code = mysqli_real_escape_string ($dbc, $_GET['invite']);

ex:

$dbc = mysqli_connect("localhost", "my_user", "my_password", "world");

Warning: mysqli_error() expects parameter 1 to be mysqli, null given in /users/mikadoru/www/register.php on line 16

You are not opening any DB!

From PHP manual:

mysqli_connect($db_host,$db_user,$db_pass,$db_database,$db_port);

Warning: mysqli_error() expects parameter 1 to be mysqli, null given in

Look at this line:

mysqli_query($db_mysqli_connection,$query) or die(mysqli_error($connection).$query);

You are using $db_mysqli_connection to connect, but $connection to check for error. You must replace $connection with $db_mysqli_connection.

Warning: mysqli_error() expects parameter 1 to be mysqli, string given in

There are three main problems with your code:

1. Wrong SQL. You have to learn basic SQL syntax prior trying to use SQL from PHP.
2. Wrong mysqli syntax. You have to use prepared statements instead of adding variables right in the query.
3. Wrong error reporting. You have to set mysqli in exception mode instead of checking every query result manually.

To solve them one by one, read these three helpful answers:

1. When to use single quotes, double quotes, and backticks in MySQL
2. How can I prevent SQL injection in PHP?
3. How to get mysqli error in different environments?

PHP mysqli_query() expects parameter 1 to be mysqli, null given in

Assuming your connection class is in 'connection.php',

class connector {

    private $db_handle; //db handles are not strings. Unsure why you were setting this to a string by default.
    private $user_name;
    private $password;
    private $database;
    public static $server = "127.0.0.1"; 
    //I'd recommend against this, unless you know 100% that your live server will use 'localhost'

    function __construct($user_name="", $password="", $database="") 
    {
        $this->user_name = $user_name;
        $this->password = $password;
        $this->database = $database;
        //There really isn't a need to not have your connector here - but that's me being lazy.
        $this->db_handle = mysqli_connect(self::$server,$this->user_name, $this->password, $this->database);
        
    }
    
    function query($sql){
        //Do some checks, or if you use prepared statements, accept the prepared data array and parse it here.
        return mysqli_query($this->db_handle, $sql);
    }

    function __destruct() 
    {
        mysqli_close($this->db_handle);
    }

}

Then, in your page, do this:

include 'connector.php';

$db = new connector('user','pw','some_db');
$query = $db->query('DELETE FROM table WHERE user_id='.$_POST['something']);
//FOR THE LOVE OF GOD, DO NOT ACTUALLY DO THIS. I DID IT ONLY FOR THE SAKE OF BREVITY. USING RAW DATA SUBMITTED FROM THE USER
// IS DANGEROUS AND LEADS TO SQL INJECTIONS. *ALWAYS* SANITIZE YOUR DATA.

The reason is add the mysqli_connect and mysqli_close calls in the __construct and __destruct methods accordingly is because I am incredibly lazy and do not want to have to call a ->connect() method. And to be honest, my laziness has sometimes saved me a lot of work because I do not want to have to repeat myself over and over again (found out this is a coding philosophy called DRY - Don't Repeat Yourself).

How can I find the execution time of a section of my program in C?

You referred to clock() and time() - were you looking for gettimeofday()?
That will fill in a struct timeval, which contains seconds and microseconds.

Of course the actual resolution is up to the hardware.

PHP.ini causes Warning: mysqli_error() expects parameter 1 to be mysqli, null given in/sys/index.php on line 19

You can use

function consql(&$con){
  $con=mysqli_connect("host","BDusername","DBPassWord","DB") or die( mysqli_error($con));
}

So this is call by reference and $con can use at any page once you call the function

Or use global $con; before the connection line

Warning: mysqli_error() expects exactly 1 parameter, 0 given error

mysqli_error() needs you to pass the connection to the database as a parameter. Documentation here has some helpful examples:

http://php.net/manual/en/mysqli.error.php

Try altering your problem line like so and you should be in good shape:

$query = mysqli_query($myConnection, $sqlCommand) or die (mysqli_error($myConnection)); 

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