Question

Below is my code under db.php

    <?php
$con = mysqli_connect('localhost', 'root', '', 'mydb');

/* check connection */
if (!$con) {
    printf("Connect failed: %s\n", mysqli_connect_error());
    exit();
}

?>

Under index.php I include db.php and functions.php as:

include("includes/db.php");
include("includes/functions.php");

functions.php is also using the db.php connection. I don’t have problem before when using mysql. But after I change mysql to mysqli I got an error “Warning: mysqli_query() expects parameter 1 to be mysqli, null given in” in my functions.php.

This is the function under functions.php that has an error:

function get_type($r_id){
    $result=mysqli_query($con, "select type from rooms where id=$r_id") or die("select type from rooms where id=$r_id"."<br/><br/>".mysqli_error());
    $row=mysqli_fetch_assoc($result);
    return $row['type'];
}

My solution is to add db.php in every function under functions.php that calls mysqli like:

function get_type($r_id){
    include("includes/db.php");
    $result=mysqli_query($con, "select type from rooms where id=$r_id") or die("select type from rooms where id=$r_id"."<br/><br/>".mysqli_error());
    $row=mysqli_fetch_assoc($result);
    return $row['type'];
}

I am wondering if this is the correct solution.

Answer 1

The problem is that $con is not available to your functions

You can add another argument to each function

function get_type($con, $r_id)...

and then pass $con into it

include('includes/db.php');
include('includes/functions.php');
$blah = get_type($con, 5);

OR

You can make $con accessible to each function by adding this global $con; for example

function get_type($r_id){
    global $con;
    $result=mysqli_query($con, "select type from rooms where id=$r_id") or die("select type from rooms where id=$r_id"."<br/><br/>".mysqli_error());
    $row=mysqli_fetch_assoc($result);
    return $row['type'];
}

The choice my friend.. is yours

(there may be other ways to skin this cat)