Notice: Variable seems to be uninitialized - php

Question

For some reason I am getting this notice in my code.
Variable $conn seems to be uninitialized
I don't understand why I'm seeing this notice. I think I'm including my include in the right place.
Class Calendar {
public function show() {
include './includes/dbconn.php';
include_once './includes/functions.php';
for ($i=0; $i<$weeksInMonth; $i++) {
// Create days in a week
for ($j=1;$j<=7;$j++) {
$cal_date = (string)$this->currentDate;
$tutor_date = display_tutor_schedule($conn,$cal_date);
if(isset($tutor_date[$j]['date'])) {
$content .= $this->_showDay($i*7+$j, $tutor_date[$j]['date']);
}
else {
$content .= $this->_showDay($i*7+$j, 0);
}
}
$content .="</tr>";
}
}
}
My $conn variable is coming from include './includes/dbconn.php';. Since I am not getting any PHP database error, such as "Not connected to the database" or something like that, I assume that my connection is right.
functions.php
function display_tutor_schedule($conn,$tutor_date) {
$query = "select * from [dbo].[TUTOR_SCHEDULE] "
. "LEFT JOIN [dbo].[TUTOR] "
. "ON [dbo].[TUTOR_SCHEDULE].tutor_id = [dbo].[TUTOR].tutor_id "
. "LEFT JOIN [dbo].[STATUS] "
. "ON [dbo].[STATUS].status_id = [dbo].[TUTOR_SCHEDULE].status_id "
. "WHERE [dbo].[TUTOR_SCHEDULE].date = '$tutor_date' " ;
$stmt = sqlsrv_query($conn, $query);
$i = 0;
$appt_detail = array();
while ($row = sqlsrv_fetch_array($stmt)) {
$appt_detail[$i]['date'] = $row['date'];
$appt_detail[$i]['t_shedule_id'] = $row['t_shedule_id'];
$appt_detail[$i]['start_time'] = $row['start_time'];
$appt_detail[$i]['end_time'] = $row['end_time'];
$appt_detail[$i]['tutor_fname'] = $row['tutor_fname'];
$appt_detail[$i]['tutor_lname'] = $row['tutor_lname'];
$appt_detail[$i]['status_name'] = $row['status_name'];
$appt_detail[$i]['status_id'] = $row['status_id'];
$i++;
}
return $appt_detail;
}
my_class.php
<?php
$calendar = new Calendar();
echo $calendar->show();
?>
dbconn.php
$serverName = "myserver";
$connectionInfo = array("Database" => "my_database", "UID" => "user", "PWD" => "pwd");
$conn = sqlsrv_connect($serverName, $connectionInfo);

Answer 1

If you are using NetBeans or PhpStorm, then this might be IDE issue.
Check https://netbeans.org/projects/php/lists/users/archive/2013-03/message/49 and PhpStorm warning PHP variable might not have been defined
However, it is advisable that you show us the files you include to check them.

Answer 2

Don't use includes or global for your variables. It's bad.
Instead you should be using classes:
class Database {
private $conn;
public function __construct(){
$serverName = "myserver";
$connectionInfo = array("Database" => "my_database",
"UID" => "user",
"PWD" => "pwd");
$this->conn = sqlsrv_connect($serverName, $connectionInfo);
}
public function get_connection(){
return $this->conn;
}
}
Calendar.php
class Calendar
{
private $conn;
public $weeksInMonth;
function __construct($conn){
$this->conn = $conn;
}
public function show()
{
$content = "";
for ($i = 0; $i < $this->weeksInMonth; $i++) {
//Create days in a week
for ($j = 1; $j <= 7; $j++) {
$cal_date = (string)$this->currentDate;
$tutor_date = display_tutor_schedule($cal_date);
if (isset($tutor_date[$j]['date'])) {
$content .= $this->_showDay($i * 7 + $j, $tutor_date[$j]['date']);
} else {
$content .= $this->_showDay($i * 7 + $j, 0);
}
}
$content .= "</tr>";
}
return $content;
}
function display_tutor_schedule($tutor_date)
{
$query = "select * from [dbo].[TUTOR_SCHEDULE] "
. "LEFT JOIN [dbo].[TUTOR] "
. "ON [dbo].[TUTOR_SCHEDULE].tutor_id = [dbo].[TUTOR].tutor_id "
. "LEFT JOIN [dbo].[STATUS] "
. "ON [dbo].[STATUS].status_id = [dbo].[TUTOR_SCHEDULE].status_id "
. "WHERE [dbo].[TUTOR_SCHEDULE].date = '$tutor_date' ";
$stmt = sqlsrv_query($this->conn, $query);
$appt_detail = array();
while ($row = sqlsrv_fetch_array($stmt)) {
$appt_detail[] = $row;
}
return $appt_detail;
}
}
Usage
$db = new Database();
$conn = $db->get_connection();
$calendar = new Calendar($conn);
$calendar->weeksInMonth = 4;
echo $calendar->show();

Answer 3

Since the variable is first initialized in the dbconn.php, the IDE might not recognize it. Insert
$conn = null;
after the line
public function show() {