Storing data from query in $_SESSION - php

Question

I've looked everywhere but most solutions are outdated or confusing.
After a user's email and passwords match, their name and id are also saved then they are sent to their homepage.
<?php
session_start();
$con=mysqli_connect("localhost", "root", "", "projectinnovations");
//Check connection
if (mysqli_connect_errno())
{
echo "Failed to connect to MySQL:" . mysqli_connect_errno();
}
if($_SERVER["REQUEST_METHOD"] == "POST")
{
$email = mysqli_real_escape_string($con,$_POST['email']);
$password = mysqli_real_escape_string($con,$_POST['password']);
$email = stripslashes($email);
$password = stripslashes($password);
$sql="SELECT * FROM individual_users WHERE email='$email' and password='$password'";
$result=mysqli_query($con,$sql);
$count=mysqli_num_rows($result);
if ($count==1)
{
$_SESSION['email']= $email;
$_SESSION['password']= $password;
$sql1="SELECT fullname FROM individual_users WHERE email='$email' and password='$password'";
$result1=mysqli_query($con,$sql1);
$_SESSION['fullname']= mysqli_fetch($result1);
$sql2="SELECT id FROM individual_users WHERE email='$email' and password='$password'";
$result2=mysqli_query($con,$sql2);
$_SESSION['id']= mysqli_fetch($result2);
header("location:home.php");
}
else
{
header("location:login.php");
}
}
mysqli_close($con);
?>

Answer 1

In order to make dealing with the session possible add session_start(); to the top of your script.

Answer 2

You haven't started the session
The simple answer is that you need to put session_start() at the top of the script (and the top of any script that uses the session variables).
But really, you don't need to do this...
The better answer is that what you're doing looks dangerously like relying on globals, and there's no reason to keep things like user e-mail addresses as global variables. Consider taking another look at your application architecture to see why you need to do this.
What could you do instead?
You'd be better off creating a User class which has the variables you need, then creating an instance of that class whenever you need access to user data.
If your worry is database congestion, look into memcached or APCu to lighten the load.
Other issues
If this is real code, you should be using password_hash and password_verify to handle login. Currently, you are storing passwords in plaintext, free for any hacker to look at.
You should also look into binding parameters in queries, which would allow you to avoid having to think about escaping values before running queries.