Get FALSE value when I insert data into mysql database - php

Question

When I just insert the username and password into my sql database, everything is okay but I get FALSE value when I try to add user's full name and company. I am not sure whether the way I bind variables to the prepared statement as parameters is correct or not. Can anyone please help me have a look on my code ? Thanks in advance!
<?php
// Include config file
require_once "config.php";
// Define variables and initialize with empty values
$username = $full_name = $company = $password = $confirm_password = "";
$username_err = $full_name_err = $company_err =$password_err = $confirm_password_err = "";
// Processing form data when form is submitted
if($_SERVER["REQUEST_METHOD"] == "POST"){
// Validate username
if(empty(trim($_POST["username"]))){
$username_err = "Please enter a username.";
} else{
// Prepare a select statement
$sql = "SELECT id FROM users WHERE username = ?";
if($stmt = mysqli_prepare($link, $sql)){
// Bind variables to the prepared statement as parameters
mysqli_stmt_bind_param($stmt, "s", $param_username);
// Set parameters
$param_username = trim($_POST["username"]);
// Attempt to execute the prepared statement
if(mysqli_stmt_execute($stmt)){
/* store result */
mysqli_stmt_store_result($stmt);
if(mysqli_stmt_num_rows($stmt) == 1){
$username_err = "This username is already taken.";
} else{
$username = trim($_POST["username"]);
}
} else{
echo "Oops! Something went wrong. Please try again later.";
}
}
// Close statement
mysqli_stmt_close($stmt);
}
// Validate full name
if(empty(trim($_POST["full_name"]))){
$full_name_err = "Please enter your full name.";
} else{
// Prepare a select statement
$sql = "SELECT id FROM users WHERE full_name = ?";
if($stmt = mysqli_prepare($link, $sql)){
// Bind variables to the prepared statement as parameters
mysqli_stmt_bind_param($stmt, "s", $param_full_name);
// Set parameters
$param_full_name = trim($_POST["full_name"]);
// Attempt to execute the prepared statement
if(mysqli_stmt_execute($stmt)){
/* store result */
mysqli_stmt_store_result($stmt);
if(mysqli_stmt_num_rows($stmt) == 1){
$full_name_err = "The name is already taken.";
} else{
$full_name = trim($_POST["full_name"]);
}
} else{
echo "Oops! Something went wrong. Please try again later.";
}
}
// Close statement
mysqli_stmt_close($stmt);
}
// Validate company
if(empty(trim($_POST["company"]))){
$company_err = "Please enter your company.";
} else{ $company = trim($_POST["company"]);}
// Validate password
if(empty(trim($_POST["password"]))){
$password_err = "Please enter a password.";
} elseif(strlen(trim($_POST["password"])) < 2){
$password_err = "Password must have atleast 6 characters.";
} else{
$password = trim($_POST["password"]);
}
// Validate confirm password
if(empty(trim($_POST["confirm_password"]))){
$confirm_password_err = "Please confirm password.";
} else{
$confirm_password = trim($_POST["confirm_password"]);
if(empty($password_err) && ($password != $confirm_password)){
$confirm_password_err = "Password did not match.";
}
}
// Check input errors before inserting in database
if(empty($username_err) && empty($password_err) && empty($confirm_password_err)&& empty($full_name_err)&& empty($company_err)){
// Prepare an insert statement
$sql = "INSERT INTO users (username,full_name, company, password) VALUES (?,?,?,?)";
if($stmt = mysqli_prepare($link, $sql)){
// Set parameters
$param_username = $username;
$param_full_name = $full_name;
$param_company = $company;
$param_password = password_hash($password, PASSWORD_DEFAULT); // Creates a password hash
// Bind variables to the prepared statement as parameters
mysqli_stmt_bind_param($stmt, "ssss", $param_username,$param_full_name,$param_company, $param_password);
// Attempt to execute the prepared statement
if(mysqli_stmt_execute($stmt)){
// Redirect to login page
header("location: login.php");
} else{
echo "Something went wrong. Please try again later.";
}
// Close statement
mysqli_stmt_close($stmt);
}
}
// Close connection
mysqli_close($link);
}
?>