PHP check if form is already submitted using num rows - php

Question

I know the problem, But I cannot seem to fix it, and I was hoping someone on here could steer me in the right direction, What I want to do is check to see if a user has already submitted a correct answer to a question before checking it against the answers database and inserting it into the database, Simply to stop the same question being answered multiple times, I am a rookie with MYSQLi and not great at it, still learning it.
What I currently have so far is :
$mysqli = new mysqli($host,$username,$password,$database);
if($mysqli -> connect_error)die($mysqli->connect_error);
$questionID = $_POST['id'];
$userAnswer = $_POST['answer'];
$userAnswer = strtolower(trim($userAnswer));
$questionValue = $_POST['qValue'];
$teamName = $_SESSION['user_email'];
$user_id = "SELECT t.teamID,t.questionGroupID FROM team as t WHERE t.teamName ='$teamName'";
$result2 = $mysqli->query($user_id);
if ($result2->num_rows > 0) {
// output data of each row
while($row = $result2->fetch_assoc()) {
$userID = $row["teamID"];
}
}
$query = "SELECT answers FROM answers WHERE questionID=?";
$statement = $mysqli->prepare($query);
$statement ->bind_param('i', $questionID);
$statement->execute();
$statement->bind_result($answer);
//checking the database to see if the current question is there from the current user/teamName
if ($result = mysqli_query($mysqli, "SELECT * FROM submissions where teamID='$teamName' and questionID='$questionID'")) {
/* determine number of rows result set */
$row_cnt = mysqli_num_rows($result);
/* close result set */
mysqli_free_result($result);
}
/* close connection */
mysqli_close($mysqli);
//checking to see if it returns a result
if(($row_cnt)= 0){
while ($statement->fetch()) {
if ($answer != $userAnswer) {
echo '<br><br><div class="alert alert-danger"><h5>
<strong>Sorry!</strong> the answer is incorrect! Please Try again!.</h5>
</div>';
"<h3>Sorry the answer is incorrect! Please Try again!</h3><br>";
//return to previous Page
echo 'Return to Question ';
$statement->free_result();
$sql = "INSERT INTO `submissions`(`submissionsID`, `teamID`, `questionID`, `answer`,`qValue`,`status`,`timestamp`) VALUES (null,'$teamName','$questionID','$userAnswer','0','Wrong',NOW())";
if (mysqli_query($mysqli, $sql)) {
} else {
echo "Error: " . $sql . "<br>" . mysqli_error($mysqli);
}
} else {
echo '<br><br><div class="alert alert-success"><h5>
<strong>Success!</strong> Correct Answer, Good Luck with the Next </h5>
</div>';
echo "<a href='questionList.php' class='btn btn-success btn-block'>Continue with other questions! </a>";
$statement->free_result();
//MySqli Insert Query
$sql = "INSERT INTO `submissions`(`submissionsID`, `teamID`, `questionID`, `answer`,`qValue`,`status`,`timestamp`) VALUES (null,'$teamName','$questionID','$userAnswer','$questionValue','Correct',NOW())";
if (mysqli_query($mysqli, $sql)) {
} else {
echo "Error: " . $sql . "<br>" . mysqli_error($mysqli);
}
}
}
}else{
echo '<br><br><div class="alert alert-warning"><h5>
<strong>Already Answered!</strong> Good Luck with the Next </h5>
</div>';
echo "<a href='questionList.php' class='btn btn-warning btn-block'>Continue with other questions! </a>";
}
I have tested it most ways, What I need to do is run a check to see if the current logged in user has already answered the questionID correctly, I am using a num_rows to see if its greater than 0, If it is greater than 0, they have answered it.
So my question is, Am I approaching it correctly, and what approach should I take?

Answer 1

It's a good approach. Try using
$row_cnt = $result->num_rows;
rather than
$row_cnt = mysqli_numrows($result);
also don't forget that $row_cnt will equal -1 in the event of any form of query error so you should check for that before assuming all values that arn't 0 are valid.

Answer 2

I would suggest you to see natural language processing (NLP) techniques. If your answer is uni-gram (one word). This approach is ok. If you are dealing with n-grams of size more than 1,ie long sentences or paragraphs Then your approach will not work well. Answers can be written in different ways. So i would suggest some semantic methods like LSA(Latent Semantic Analysis) or simple vector representation models.
I can't think of any other methods to solve this problem.Try NLP methods. Will give you awesome results.

Answer 3

I took a different approach to trying to get it to work and finally got it working, Just wanted to post my solution and thank everyone for helping.
<?php session_start(); ?>
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1">
<meta name="description" content="">
<meta name="author" content="">
<!-- Bootstrap Core CSS -->
<link href="css/bootstrap.min.css" rel="stylesheet">
<!-- Custom CSS -->
<link href="css/modern-business.css" rel="stylesheet">
<!-- Custom Fonts -->
<link href="font-awesome/css/font-awesome.min.css" rel="stylesheet" type="text/css">
<!-- HTML5 Shim and Respond.js IE8 support of HTML5 elements and media queries -->
<!--[if lt IE 9]>
<script src="https://oss.maxcdn.com/libs/html5shiv/3.7.0/html5shiv.js"></script>
<script src="https://oss.maxcdn.com/libs/respond.js/1.4.2/respond.min.js"></script>
<![endif]-->
</head>
<body>
<!-- Navigation -->
<?php include_once('navigation.php');
// establishing the MySQLi connection
require_once('connection-test.php');
$mysqli = new mysqli($host,$username,$password,$database);
/* check connection */
if (mysqli_connect_errno()) {
printf("Connect failed: %s\n", mysqli_connect_error());
exit();
}
$questionID = $_POST['id'];
$userAnswer = $_POST['answer'];
$userAnswer = strtolower(trim($userAnswer));
$questionValue = $_POST['qValue'];
$teamName = $_SESSION['user_email'];
$user_id = "SELECT t.teamID,t.questionGroupID FROM team as t WHERE t.teamName ='$teamName'";
$result2 = $mysqli->query($user_id);
if ($result2->num_rows > 0) {
// output data of each row
while($row = $result2->fetch_assoc()) {
$userID = $row["teamID"];
}
}
$query = "SELECT answers FROM answers WHERE questionID=?";
$statement = $mysqli->prepare($query);
$statement ->bind_param('i', $questionID);
$statement->execute();
$statement->bind_result($answer);
$statement->store_result();
?>
<div class="container">
<!-- Page Content -->
<hr>
<?php
if ($result4 = $mysqli->query("SELECT * FROM submissions where teamID='$teamName' and questionID='$questionID'"))
{
// display records if there are records to display
if ($result4->num_rows > 0)
{
echo '<br><br><div class="alert alert-warning"><h5>
<strong>Already Answered!</strong> Good Luck with the Next </h5>
</div>';
echo "<a href='questionList.php' class='btn btn-warning btn-block'>Continue with other questions! </a>";
}
// if there are no records in the database, display an alert message
else
{
while ($statement->fetch()) {
if ($answer != $userAnswer) {
echo '<br><br><div class="alert alert-danger"><h5>
<strong>Sorry!</strong> the answer is incorrect! Please Try again!.</h5>
</div>';
"<h3>Sorry the answer is incorrect! Please Try again!</h3><br>";
//return to previous Page
echo 'Return to Question ';
$statement->free_result();
$sql = "INSERT INTO `submissions`(`submissionsID`, `teamID`, `questionID`, `answer`,`qValue`,`status`,`timestamp`) VALUES (null,'$teamName','$questionID','$userAnswer','0','Wrong',NOW())";
if (mysqli_query($mysqli, $sql)) {
} else {
echo "Error: " . $sql . "<br>" . mysqli_error($mysqli);
}
} else {
echo '<br><br><div class="alert alert-success"><h5>
<strong>Success!</strong> Correct Answer, Good Luck with the Next </h5>
</div>';
echo "<a href='questionList.php' class='btn btn-success btn-block'>Continue with other questions! </a>";
$statement->free_result();
//MySqli Insert Query
$sql = "INSERT INTO `submissions`(`submissionsID`, `teamID`, `questionID`, `answer`,`qValue`,`status`,`timestamp`) VALUES (null,'$teamName','$questionID','$userAnswer','$questionValue','Correct',NOW())";
if (mysqli_query($mysqli, $sql)) {
} else {
echo "Error: " . $sql . "<br>" . mysqli_error($mysqli);
}
}
}
}
}
// show an error if there is an issue with the database query
else
{
echo "<strong>Error:</strong>" . $mysqli->error;
}
?>
<?php include_once('footer.php'); ?>
</div>
<!-- /.container -->
<!-- jQuery -->
<script src="js/jquery.js"></script>
<!-- Bootstrap Core JavaScript -->
<script src="js/bootstrap.min.js"></script>
</body>
</html>