controller / model不会返回true结果

I'm trying to update result in the database.The Update query is working fine, values are getting updated but controller show else results always.

Below code

base Controller

#update/save in model
$data = ['twitter_link' => $this->input->post('twitter_link')];
if($this->Restaurant_admin->update_site_settings($data,'setting_id',1,'site_setting')){ 
    $this->session->set_flashdata("update_success_twitter","Twitter link updated successfully.");
    redirect('admin/Entry/basic_table');
}else{
    $this->session->set_flashdata("update_success_twitter","Something went wrong data not saved.");
    redirect('admin/Entry/basic_table');
}

Restaurant_admin Model

public function update_site_settings($data,$where_cond,$value,$table_name)
{
    $this->db->set($data);
    $this->db->where($where_cond,$value);
    $this->db->update($table_name,$data);      
}   
#update_site_settings

In model update_site_settings function check the query is executed or not, If executed successfully return true else return false

public function update_site_settings($data,$where_cond,$value,$table_name)
{
    $this->db->set($data);
    $this->db->where($where_cond,$value);
    if($this->db->update($table_name,$data))
    {
        return true;
    }
    else
    {
        return false;
    }
}