Untitled

<?php
$error = [];
$result = null;
if (isset($_POST['signupBtn'])){

    $name = trim($_POST['name']);
    $email = trim($_POST['email']);
    $hashed_password = password_hash($pwd, PASSWORD_DEFAULT);

    // check if user already exist
    $statement = $dbh->prepare("SELECT username FROM signup WHERE username =: name");
    $statement->bindParam(':name', $name);

    if ($statement->execute()) {
        if ($statement->rowCount() > 0) {
            $error[] = 'User Name Taken";
        }
    } else {
        $error[] = 'System Error 1";
    }

    $statement = $dbh->prepare("SELECT username FROM signup WHERE email = :email");
    $statement->bindParam(':email', $email);

    if ($statement->execute()) {
        if ($statement->rowCount() > 0) {
            $error[] = 'Email Address Taken";
        }
    } else {
        $error[] = 'System Error 2";
    }

    // you cannot use if/else since you can have username exists OR email exists OR both

    if (!$error) {
        $insert="INSERT INTO signup(username, email, password) VALUES(:name, :email, :pwd)";
        $statement = $dbh->prepare($insert);
        $statement->bindParam(':name', $name);
        $statement->bindParam(':email', $email);
        $statement->bindParam(':pwd', $hashed_password);
        if ($statement->execute() && $statement->rowCount() > 0) {
            $result = "row inserted";
        } else {
            $result = "insertion failed";
        }
    }
}
?>
<html>
<div class="form-group">
            <label for="exampleInputUsername">Username</label>
            <input type="text" name="name" class="form-control" id="exampleInputUsername" placeholder="enter username">
            <span class="error_message"><?php echo $nameErr;?></span>
          </div>

          <div class="form-group">
              <label for="exampleInputEmail1">Email address</label>
              <input type="email" name="email" class="form-control" id="exampleInputEmail1" aria-describedby="emailHelp" placeholder="Enter email">
              <span class="error_message"><?php echo $emailErr;?></span>
              <small id="emailHelp" class="form-text text-muted">We'll never share your email with anyone else.</small>
            </div>

    <button type="submit" name="signupBtn" class="btn btn-primary">SIGNUP</button>
    <?php echo $implode('<br>', $error); ?>
    <?php echo $result; ?>
</html>