Validation.php

<?php
   error_reporting(E_ALL);
   ini_set("display_errors", 1);
// Include config file


// Define variables and initialize with empty values

$username_err = $password_err = $confirm_password_err = $passwordConf_err = $email_err = $email_used_err = "";

$username = $password = $email = "";
$param_password = $param_username =$param_email = "";
$passwordConf = "";



// 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{
		require_once "db_conn.php";
        // Prepare a select statement
        $sql = "SELECT id FROM estiweb_db 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($stmt);
    }
//validate email
    if(empty(trim($_POST["email"]))){
        $email_err = "Please fill in the Email!";
    } else{
		require_once "db_conn.php";
        // Prepare a select statement
        $sql = "SELECT id FROM estiweb_db WHERE email = ?";

        if($stmt = mysqli_prepare($link, $sql)){
            // Bind variables to the prepared statement as parameters
            mysqli_stmt_bind_param($stmt, "s", $param_email);

            // Set parameters
            $param_email = trim($_POST["email"]);

            // 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){
                    $email_used_err = "This email is already in use!";
                } else{
                    $email = trim($_POST["email"]);
                }
            } else{
                echo "Oops! Something went wrong. Please try again later.";
            }


        // Close statement
        mysqli_stmt_close($stmt);
    }
    // Validate password
    if(empty(trim($_POST["password"]))){
        $password_err = "Please enter a password.";
    } elseif(strlen(trim($_POST["password"])) < 6){
        $password_err = "Password must have atleast 6 characters.";
    } else{
        $password = trim($_POST["password"]);
    }

    // Validate confirm password
    if(empty(trim($_POST["passwordConf"]))){
        $passwordConf_err = "Please confirm password.";
    } else{
        $passwordConf = trim($_POST["passwordConf"]);
        if(empty($password_err) && ($password != $passwordConf)){
            $confirm_password_err = "Password did not match.";
        }
    }
		/*
    echo $username_err;
    echo $password_err;
    echo $email_err;
	*/
    // Check input errors before inserting in database
    if(empty($username_err) && empty($password_err) && empty($email_err) && empty($confirm_password_err) && empty($passwordConf_err)){
        require_once "db_conn.php";
        // Prepare an insert statement
		$sql = mysqli_query("INSERT INTO estiweb_db (username, email, password) VALUES (? ,?, ?)");

        if($stmt = mysqli_prepare($link, $sql)){
            // Bind variables to the prepared statement as parameters
            mysqli_stmt_bind_param($stmt, "sss", $param_username, $param_email, $param_password);

            // Set parameters
            $param_username = $username;
            $param_password = password_hash($password, PASSWORD_DEFAULT); // Creates a password hash
            $param_email = $email;

            // Attempt to execute the prepared statement

			if ($link->query($stmt) === TRUE) {
				//header("location: ../login.php")
				echo "New record created successfully";
				} else {
    		echo "Error: " . $sql . "<br>" . $conn->error;
				}
            } else{
                echo "Something went wrong. Please try again later.";
            }
        }

        // Close statement
        mysqli_stmt_close($stmt);
    }

    // Close connection
    mysqli_close($link);
	}
}
?>