CodeIgniter中的两个带有if语句的插入查询

我试图通过检查用户类型来在两个表中添加信息。若用户为普通用户，则必须在第一个表中输入记录；若用户类型为医生，则必须将记录输入两个表中。我在CodeIgniter 3.6 工作

public function model_signup()
{
$nameVar                = $this->input->post("signup_name");
$emailVar           = $this->input->post("signup_email");
$phoneVar           = $this->input->post("signup_phone");
$passwordVar            = $this->input->post("signup_password");
$ifDoctorVar            = $this->input->post("signup_ifdoctor");
$pmdcVar                = $this->input->post("signup_pmdc");
$signu_query            = $this->db->query("SELECT * FROM `doc_users` WHERE `user_email`='".$emailVar."'");
if($signu_query->num_rows() >0){
return false;
}
else
{
   $this->db->query("INSERT INTO `doc_users`
   (`user_nicename`,
   `user_login`,
   `user_email`,
   `display_name`,
   `user_phone`,
   `user_pass`,
   `user_type`,
   `user_registered`)
   VALUES ('$nameVar',
   '$emailVar',
   '$emailVar',
   '$nameVar',
   '$phoneVar',
   '$passwordVar',
   '$ifDoctorVar',
   NOW())");
    $user_id = $this->db->insert_id();
   if($ifDoctorVar=='Doctor') {    // checking if user is doctor or not
   $this->db->query("INSERT INTO `doc_doc_details`
   (`ID`,
   `pmdc_id`,
   `email`,
   `phone)
   VALUES ('$user_id',
   '$pmdcVar',
   '$emailVar',
   '$phoneVar')");
  return true;
   }
  }
 }