How to Connect database MySql using PHP?

Question

I followed a lot of tutorial on google/youtube but still unable to connect database using php. I coded exactly according to documentation for database connection but it doesn,t work.I have already created database named as userregistration using mysql dashboard. Here is myindex.html file:

 <!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>User Login and Registration</title>
<link rel="stylesheet" type="text/css" href="style.css">
<link rel="stylesheet" type="text/css"   href="https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/css/bootstrap.min.css">
</head>
<body>
<div class="container">
    <div class="login-box">
    <div class="row">
        <div class="col-md-6 login-left">
            <h2>Login Here</h2>
            <form action="validation.php" method="post">
                <div class="form-group">
                    <label>Username</label>
                    <input type="text" name="user" class="form-control" required>
                </div>
                <div class="form-group">
                    <label>Password</label>
                    <input type="password" name="password" class="form-control" required>
                </div>
                <button type="submit" class="btn btn-primary">Login</button>

            </form>

        </div>
        <div class="col-md-6 login-right">
            <h2>Register Here</h2>
            <form action="registration.php" method="post">
                <div class="form-group">
                    <label>Username</label>
                    <input type="text" name="user" class="form-control" required>
                </div>
                <div class="form-group">
                    <label>Password</label>
                    <input type="password" name="password" class="form-control" required>
                </div>
                <button type="submit" class="btn btn-primary">Register</button>

            </form>

        </div>
    </div>
    </div>
</div>
</body>
</html>

Here is my Registration.php file:

<?php

session_start();

$con = mysqli_connect('localhost','root','');
mysqli_select_db($con, 'userregistration');
$name = $_POST['user'];
$pass = $_POST['password'];

$s = "select * from  usertable where name='$name'";
$result = mysqli_query($con, $s);
$num = mysqli_num_rows($result);

if($num == 1){
    echo "Username Already Taken";
}else{
    $reg = "insert into usertable(name, password) values ('$name','$pass')";
    mysqli_query($con, $reg);
    echo "Registration Successful";
}
?>

Is there any error in my code?

Didn't work is not a very helpful error description, what message the website gave when you submit your registration form? — catcon
– catcon, Commented Sep 30, 2019 at 6:31
how do you structure your project? action="registration.php" say it will look for the file registration.php in the same folder of the HTML file — catcon
– catcon, Commented Sep 30, 2019 at 6:37
If you are on a *nix platform, file names are case sensitive as you have registration.php in your code and the file name you show as Registration.php (although this may be just in the question). — Nigel Ren
– Nigel Ren, Commented Sep 30, 2019 at 6:38
@NigelRen yeah this name is just in question. I,m using registration.php in small case in my project — Javed Abrar
– Javed Abrar, Commented Sep 30, 2019 at 6:42

ScaisEdge · Accepted Answer · 2019-09-30 07:20:53Z

1

Try using directly the connection with db name

based on patter

$con = mysqli_connect("127.0.0.1", "my_user", "my_password", "my_db");

try

$con = mysqli_connect('localhost','root','','userregistration');

and be sure your php page is in the correct path
eventually try adding a proper path or at least a relative path

   <form action="./Registration.php" method="post">

edited Sep 30, 2019 at 7:20

answered Sep 30, 2019 at 6:29

ScaisEdge

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6 Comments

ScaisEdge Over a year ago

are you sure that username is localhost,, the password is root and the db name is userregistration check better ..anyway error 404 is not a db error but a page not found http error check for you link (and path) to the php page

Nigel Ren Over a year ago

You have missed the password out of the connect parameters.

Javed Abrar Over a year ago

no the username is not localhost. Servername is localhost, username is root, password is empy and database name is userregistration.

ScaisEdge Over a year ago

then adgiust the proper value in the right sequence answer updated ..

Javed Abrar Over a year ago

I also applied your updated code but again unfortunately it shows the same error when i click to register button(the error is 404 not found)

|

Jayden · Accepted Answer · 2019-09-30 06:42:10Z

Your PHP part looks alright. Maybe you can try to see if the PHP is able to make the connection by adding such a debugging code like how it is documented here, https://www.php.net/manual/en/function.mysqli-connect.php

if (!$con) {
    echo "Error: Unable to connect to MySQL." . PHP_EOL;
    echo "Debugging errno: " . mysqli_connect_errno() . PHP_EOL;
    echo "Debugging error: " . mysqli_connect_error() . PHP_EOL;
    exit;
}

echo "Success: A proper connection to MySQL was made! The my_db database is great." . PHP_EOL;
echo "Host information: " . mysqli_get_host_info($con) . PHP_EOL;

Finally, MOST IMPORTANTLY, you should probably not be using this directly because this can introduce serious SQL-Injection vulnerabilities. Google a little more about the best practices. :)

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