Check if username exists in mysql table via php? [duplicate] - php

Question

This question already has answers here:
Check if value exists before inserting into MySQL DB in a PHP script
(1 answer)
How to check if a row exists in MySQL? (i.e. check if username or email exists in MySQL)
(4 answers)
Closed 9 years ago.
I am trying to figure out how to have my register php code check whether or not the registee's username is already taken, and if it is, don't register it, tell the user that it's taken.
Here's my entire register processing file.
<?php
$con=mysqli_connect("localhost","root","","users");
// Check connection
if (mysqli_connect_errno())
{
echo "Failed to connect to MySQL: " . mysqli_connect_error();
}
$hpassword = hash( 'sha512', $_POST['password'] );
$eusername = mysqli_real_escape_string( $con, $_POST['username'] );
$eemail = mysqli_real_escape_string( $con, $_POST['email'] );
$fusername = str_replace(' ', '', $eusername);
$sql="INSERT INTO users (username, password, email)
VALUES
('$fusername','$hpassword','$eemail')";
if (!mysqli_query($con,$sql))
{
die('Error: ' . mysqli_error($con));
}
mysqli_close($con);
?>

Answer 1

$sql=mysql_query("SELECT FROM users (username, password, email) WHERE username=$fusername");
if(mysql_num_rows($sql)>=1)
{
echo"name already exists";
}
else
{
//insert query goes here
}
you can check from database whether user exists and then paste the code

Answer 2

include ('database_connection.php');
if (isset($_POST['formsubmitted'])) {
$error = array();
if (empty($_POST['username'])) {
$error[] = 'Please Enter a name ';
} else {
$username = $_POST['username'];
}
if (empty($_POST['e-mail'])) {
$error[] = 'Please Enter your Email ';
} else {
if (filter_var($_POST['e-mail'], FILTER_VALIDATE_EMAIL)) {
//for email validation (refer: http://us.php.net/manual/en/function.filter-var.php)
$email = $_POST['e-mail'];
} else {
$error[] = 'Your EMail Address is invalid ';
}
}
if (empty($_POST['password'])) {
$error[] = 'Please Enter Your Password ';
} else {
$password = $_POST['password'];
}
if (empty($error))
{ // If everything's OK...
$query = "SELECT * FROM members WHERE username ='$username'";
$result = mysqli_query($dbc, $query); // here $dbc is your mysqli $link
if (!$result) {
echo ' Database Error Occured ';
}
if (mysqli_num_rows($result) == 0) { // IF no previous user is using this username.
$query = "INSERT INTO `members` ( `username`, `email`, `password`) VALUES ( '$name', '$email', '$password')";
$result = mysqli_query($dbc, $query);
if (!$result) {
echo 'Query Failed ';
}
if (mysqli_affected_rows($dbc) == 1) { //If the Insert Query was successfull.
// Send an email
// Finish the page:
echo '<div class="success">Thank you for registering! A confirmation email has been sent to ' . $email . ' Please click on the Activation Link to Activate your account </div>';
} else { // If it did not run OK.
echo '<div class="errormsgbox">You could not be registered due to a system error. We apologize for any inconvenience.</div>';
}
} else { // The username is not available.
echo '<div class="errormsgbox" >That username has already been registered.
</div>';
}
} else { //If the "error" array contains error msg , display them.... e.g....
echo '<div class="errormsgbox"> <ul>';
foreach ($error as $key => $values) {
echo ' <li>' . $values . '</li>';
}
echo '</ul></div>';
}
mysqli_close($dbc); //Close the DB Connection
} // End of the main Submit conditional.

Answer 3

Either you can use Dave's way and check' the error code, or you can precheck whether the user exists
$sql="SELECT FROM users (username, password, email) WHERE username=$fusername"
Now check the results of this. If a row is fetched, then the user exists. Indicate this to the user. If not, the sun is shining on the user. Give him a cookie