使用PDO发送数据后重定向到空白页

Question

I have a survey webpage that if users done it , I will send the data they give (as $_SESSION from the other pages) and I will change his/her status to 0 (They can't do the survey after that with his/her login info.).

All of these are doing with PDO. But why the page always redirects to a white blank page?

Here is my code

<?php
session_start();
if (!isset($_SESSION['user'])) 
{
header("location:index.php");
}
?>

<?php
require_once "condb.php";
?>

<?php
if (isset($_POST['BTN_P2']))
{
  $_SESSION['problem'] = $_POST['problem'];
  if ($_SESSION['problem'] == "yes"){header("location:survey_3.php");}
else
{
  $sql="INSERT INTO data(time,suggest,phone,eat,problem) VALUES(?,?,?,?,?)";
  $stm=$cn->prepare($sql);
  $stm->bindParam("1",$_SESSION['time']);
  $stm->bindParam("2",$_SESSION['suggest']);
  $stm->bindParam("3",$_SESSION['phone']);
  $stm->bindParam("4",$_SESSION['eat']);
  $stm->bindParam("5",$_SESSION['problem']);

  try 
  {
    $stm->execute();
      try 
      {
       $sqlstatus="INSERT INTO login(status) VALUES(0)";
       $stmt=$cn->prepare($sqlstatus);
       $stmt->execute();
       echo "Finish!";
       header('location:finish.php');
      } 
      catch (Exception $error) 
      {
        echo $error->getTraceAsString();
      }
  } 
  catch (Exception $e) 
  {
    echo $e->getTraceAsString();
  }
}
}
?>

What I am missing?

Edit #1 : Verifying how $_SESSION['user'] comes from.

<?php
if (isset($_POST['BTN_ENTER']))
{
  $username=$_POST['username'];
  $password=$_POST['password'];
  $hashed_password=password_hash($password,PASSWORD_DEFAULT);
    try
    {
      $stmt = $cn->prepare("SELECT * FROM login WHERE username=:username LIMIT 1");
      $stmt->execute(array(':username'=>$username));
      $result=$stmt->fetch(PDO::FETCH_ASSOC);
      if($stmt->rowCount() > 0)
        {
          if(password_verify($password, $result['password']))
          {
            if ($result['status']==1)
              {
                $_SESSION['user']=$result['name'];
                header('location:survey.php');
              }
          }
        }
     }
     catch(PDOException $e)
     {
       echo $e->getMessage();
     }
}

Answer 1

You should try and break your scripts into functions / methods to make it easier to work with, read, reuse, etc. When you make a function, you can try it manually by itself before you implement it. Once you confirm the function works by itself, then you throw it into the logic and if something fails, you know it's not that function:

/functions/suggestEatingProblem.php

<?php
function suggestEatingProblem($con,$array)
    {
        $sql = "INSERT INTO `data` (`time`,`suggest`,`phone`,`eat`,`problem`) VALUES(?,?,?,?,?)";
        $query = $con->prepare($sql);
        # Since you are not really doing anything special with your parameters
        # just do the array into the execute function, it's more straight forward
        $query->execute($array);
    }

/functions/addLoginStatus.php

<?php
function addLoginStatus($con,$val)
    {
        # Don't need to prepare, just query
        $con->query("INSERT INTO login (`status`) VALUES({$val})");
    }

/functions/verifyUser.php

<?php
function verifyUser($con,$username,$password)
    {
        $stmt = $con->prepare("SELECT `password`,`name` FROM login WHERE username = ? LIMIT 1");
        $stmt->execute(array($username));
        $result = $stmt->fetch(PDO::FETCH_ASSOC);
        if(empty($result['password']))
            return false;

        $isValid = password_verify($password, $result['password']);
        return ($isValid)? $result['name'] : false;
    }

/config.php

<?php
# Create some helpful constants
define('DS',DIRECTORY_SEPARATOR);
define('ROOT_DIR',__DIR__);
define('FUNCTIONS',ROOT_DIR.DS.'functions');
# Start session
session_start();
# Start database
require_once(ROOT_DIR.DS."condb.php");

/whatever.php

<?php
# Add config at top
require_once(__DIR__.DIRECTORY_SEPARATOR.'config.php');
# Add our functions to be used
require_once(FUNCTIONS.DS.'suggestEatingProblem.php');
require_once(FUNCTIONS.DS.'addLoginStatus.php');
# If no session, redirect
if (!isset($_SESSION['user'])) {
    header("Location: index.php");
    # Make sure to stop your script if you are done with the page
    exit;
}
# Check if submission
if(isset($_POST['BTN_P2'])) {
    # Assign problem (trim it)
    $_SESSION['problem'] = trim($_POST['problem']);
    # If yes
    if($_SESSION['problem'] == "yes") {
        # Redirect and stop the script execution
        header("Location: survey_3.php");
        exit;
    }
    else {
        # Just do one "try" here...
        try {
            # Run your function here
            suggestEatingProblem($cn,array(
                $_SESSION['time'],
                $_SESSION['suggest'],
                $_SESSION['phone'],
                $_SESSION['eat'],
                $_SESSION['problem']
            ));
            # Run your second function here
            addLoginStatus($cn,'0');
            # Redirect. You can not put content before you redirect, so
            # remove the "Finished" echo
            header('Location: finish.php');
            exit;
        } 
        catch (PDOException $e){
            echo 'Error occurred: '.$e->getTraceAsString();
        }
    }
}
else {
    echo 'No request sent.';
}

Validation portion:

# Add function (see the other example to add the config)
require_once(FUNCTIONS.DS.'verifyUser.php');
# If there is a submission
if(isset($_POST['BTN_ENTER'])) {
    try {
        # Fetch the name (or false)
        $user = verifyUser($cn,trim($_POST['username']),trim($_POST['password']));
        # If not false
        if($user) {
            # Assign the value
            $_SESSION['user'] = $user;
            # Redirect and stop execution of script
            header('Location: survey.php');
            exit;
        }
    }
    catch(PDOException $d) {
        echo $e->getMessage();
    }
}