PHP/MYSQL Insert is doing nothing

Question

I have a simple form set up in HTML to pass values to PHP and put them in a MYSQL database. I just can't fathom why nothing is happening when I click the submit button. Previously it was saying 'failed' but now nothing. I have checked the values from the form - fine. I've checked the database connection - fine. I've checked the SQL statement - well, I can't see any errors.

This is my main HTML page

<p class="subtitle">Let me know what you think</p>
<form action="db_insert.php">
<input name="username" placeholder="Name">
<br>
<textarea name="comments" placeholder="Please type your comments here" 
cols=120 rows=5></textarea>
<br>
<input type="button" name="submit" value="submit">
<br>
<p id="commTitle">Comments</p>
<br>
<p id="comment"></p>

This is the PHP

<?php
include 'db_connection.php';

//create database connection 
$conn = OpenCon();
$username = htmlspecialchars($_POST['username']);
$comment = htmlspecialchars($_POST['comment']);

$sql = 'INSERT INTO sitecomments(username, comment) VALUES(:username,:comment)';
$stmt = $conn -> prepare($sql);
$stmt -> bindValue(':username', $username);
$stmt -> bindValue(':comment', $comment);
$q_result = $stmt -> execute();

if($q_result){
echo 'Comment Inserted Successfully';
}
else{
echo 'Failed';
}

db_connection.php looks like this (with credentials removed.

<?php

function OpenCon(){
    //pass the database details to variables
    $host = "localhost";
    $dbuser = "*****";
    $dbpass = "*****";
    $dbname = "*****";
    // combine host and db name in to single variable
    $dbhost = "mysql:host=$host;dbname=$dbname";
    //create PDO from database information
    $dbconn = new PDO($dbhost, $dbuser, $dbpass);
    return $dbconn;
}
?>

As I said, I've checked the database connection and all is fine so where on earth am I going wrong? My database has 3 fields but one is autoincremented so I haven't included it in the query. I tried the query in MyPHPAdmin and it passed ok.

Don't guess when the query fails. Instead, check for PDO errors — aynber
– aynber, Commented Feb 27, 2019 at 19:34
output the raw query that would get run, and then review it for problems / test it in mysql workbench or phpmyadmin. — Andrew
– Andrew, Commented Feb 27, 2019 at 19:36

Daniel G · Accepted Answer · 2019-02-27 19:38:40Z

1

The first thing I notice is that the input has name of "comments" rather than the $_POST variable you're accessing called comment:

<textarea name="comments" placeholder="Please type your comments here" cols=120 rows=5></textarea>

$comment = htmlspecialchars($_POST['comment']);

Try changing that and see if it fixes the issue.

answered Feb 27, 2019 at 19:38

Daniel G

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3 Comments

user3783243 Over a year ago

Even undefined it should insert an empty record.

Daniel G Over a year ago

Correct, unless the error occurs when running htmlspecialchars($_POST['comment'])

Daniel G Over a year ago

Glad to hear it @HarrySampson. If you have a chance, can you mark my answer as the Accepted Answer.

domdambrogia · Accepted Answer · 2019-02-27 19:44:14Z

It would be helpful to handle errors within your code. In your current example if something goes wrong you will have a hard time finding out where the problem is.

You can try all of the following examples from the PHP Docs on PDO error handling and PDO::errorInfo:

Assert your connection is valid:

try {
    $dbh = new PDO($dsn, $user, $password, array(PDO::ATTR_ERRMODE => PDO::ERRMODE_WARNING));
} catch (PDOException $e) {
    echo 'Connection failed: ' . $e->getMessage();
    exit;
}

Assert your SQL is valid

/* Provoke an error -- bogus SQL syntax */
$stmt = $dbh->prepare('bogus sql');
if (!$stmt) {
    echo "\nPDO::errorInfo():\n";
    print_r($dbh->errorInfo());
}

As usual the error is a pebcak error, and you need to utilize proper debugging tools to find out where your mistakes are. Good luck!

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