Variable is undefined inside a function, cannot reach MySQL $connection inside a function

Question

I have a code that works when I use it on a page but Im trying to make this a function. I cant get it to work, it seems like the variables $customer and $system arent being sent through to the code. Even if I type it in Raw. Any idea whats wrong? $Customer is the name of the customer, $system can be 'Source' or 'Target'.

function status_total($customer, $system){
        $sql_customer       = "SELECT * FROM `Customer` WHERE Cust_Name = '$customer' LIMIT 0,1";
        $customer_selection = mysqli_query($conn,$sql_customer);
        $customer_row       = mysqli_fetch_assoc($customer_selection);
        $env_lines          = $customer_row["Env_Lines"];
        $cust_id            = $customer_row["Cust_ID"];
        $sql_last_records   = "SELECT * FROM $system WHERE Cust_ID = $cust_id ORDER BY Time DESC LIMIT $env_lines";
        $record_selection   = mysqli_query($conn, $sql_last_records);               

        $result = mysqli_fetch_all($record_selection, MYSQLI_ASSOC);
        $states = array_column($result, "Stat");

        if($states == array_fill(0, count($states), "Run")) {
            echo "Success";
        } else 
            echo "Fail";

    }

https://gist.github.com/R2D2-05/78d81566e4bf0eafd1fa

Answer 1

The problem with your code is $conn variable which is treated a local variable inside a function. You should:

function status_total($customer, $system){
        global $conn;

        $sql_customer       = "SELECT * FROM `Customer` WHERE Cust_Name = '$customer' LIMIT 0,1";
        $customer_selection = mysqli_query($conn,$sql_customer);
        $customer_row       = mysqli_fetch_assoc($customer_selection);
        $env_lines          = $customer_row["Env_Lines"];
        $cust_id            = $customer_row["Cust_ID"];
        $sql_last_records   = "SELECT * FROM $system WHERE Cust_ID = $cust_id ORDER BY Time DESC LIMIT $env_lines";
        $record_selection   = mysqli_query($conn, $sql_last_records);               

        $result = mysqli_fetch_all($record_selection, MYSQLI_ASSOC);
        $states = array_column($result, "Stat");

        if($states == array_fill(0, count($states), "Run")) {
            echo "Success";
        } else 
            echo "Fail";

    }

Or you can also pass the $conn through the function, so change the function's definition to:

function status_total($conn, $customer, $system){...}