mysqli/mysql query inside function not working [duplicate] - php

Question

This question already has answers here:
Executing mysqli_query inside a function
(2 answers)
Closed 1 year ago.
I'm tryin to build some functions for a website of mine and some of them consist in
fetching data from the mysql database. When I test the code outside of the function
it seems to work properly. So here it is, The first page:
require('db.php');
require('functions.php');
$email = 'sample#gmail.com';
if (user_exists($email) == true){
echo "Good news, this exists";
}
Now db.php :
$db = new MySQLi("localhost","test","test","test");
if ($db->connect_errno){
echo "$db->connect_errno";
}
And the functions.php file:
function sanitize ($data){
$db->mysqli_real_escape_string($data);
}
function user_exists($usermail){
$usermail = sanitize($usermail);
$query = $db->query("SELECT COUNT(userId) FROM users WHERE userEmail= '$usermail' ");
$check = $query->num_rows;
return ($check == 1) ? true : false;
}
And the error I'm getting when accessing the first file is:
Notice: Undefined variable: db in C:\xampp\htdocs\auctior\inc\functions.php on line 6
Fatal error: Call to a member function query() on a non-object in C:\xampp\htdocs\auctior\inc\functions.php on line 6
SO I've required/included the db.php where $db is the mysqli connect. And within the same file(first file) I call the functions located at functions.php
Thank you in advance,
I'd appreciate your help as this is pissing me off......

Answer 1

You probably need to use the global keyword, otherwise $db is considered a var in local scope.
function sanitize ($data){
global $db;
$db->mysqli_real_escape_string($data);
}
function user_exists($usermail){
global $db;
$usermail = sanitize($usermail);
$query = $db->query("SELECT COUNT(userId) FROM users WHERE userEmail= '$usermail' ");
$check = $query->num_rows;
return ($check == 1) ? true : false;
}

Answer 2

Try to connect inside the function, and connection needs to be included before you include functions.
Something like this:
function user_exists($usermail){
$db = new MySQLi("localhost","test","test","test");
$usermail = sanitize($usermail);
$query = $db->query("SELECT COUNT(userId) FROM users WHERE userEmail= '$usermail' ");
$check = $query->num_rows;
return ($check == 1) ? true : false;
}