No se mantenie info de $_SESSION por que?

[pilucho]

Fatal error: Call to a member function query() on null in u_demo.php on line 8

Código PHP:

<?php
session_start();
include_once('conn.php'); // Coneción  
//recibo la variable cedula
$cedula = $_post['cedula'];
 
//verifico el cedula
$veri = $db->query("select * from personas where cedula = '$cedula'");
$total = mysqli_num_rows($veri);
$row = $very->fetch_assoc();
 
if($total == 1){
 
$cedula = $row['cedula'];
$nombres = $row['nombres'];
$apellidos = $row['apellidos'];
 
$_session['cedula'] = $cedula;
$_session['nombre'] = $nombres;
$_session['apellido'] = $apellidos;
 
header('location:loquesea.php');
} else{
header('location:error.php');
}
?>