Php 当用户不使用'；我不想更新所有数据库字段

假设这是我的控制器

class Admin extends CI_Controller{

    public function account(){

        // if user logged in redirect to home page
        if (!isset($this->session->userdata['loggedin']) || $this->session->userdata['userRoll'] != 'admin')
        {
            redirect (base_url());
        }

        if($this->input->method() == "post")
        {

            //store all settings
            $adminfullname =  $this->input->post('admin-fullname');
            $adminemail =  $this->input->post('admin-email');
            $adminpass =  $this->input->post('admin-pass');


            //load the validation library
            $this->load->library('form_validation');

            $this->form_validation->set_rules('admin-fullname', 'Full Name', 'required');
            $this->form_validation->set_rules('admin-email', 'Admin Email', 'required|valid_email|callback__checkMail');



            //check validation error
            if ($this->form_validation->run() == FALSE)
            {


                //get the all settings from database and store it to variable
                $data['site'] = $this->settings_model->SiteSettings(); 


                $this->load->view("layout/header",$data);
                $this->load->view("admineditaccount",$data);
                $this->load->view("layout/footer",$data);
            }

            else
            {
                //update user account
                $updateAccount = $this->admin_model->updateAccount($adminfullname,$adminemail,$adminpass);

                if($updateAccount){
                    $this->session->set_userdata('username', $fullname);
                    $this->session->set_userdata('email', $adminemail);

                    $data['msg'] ='<div class="alert slert-success">Successfully Updated</div>';

                }else
                {
                    $data['msg'] ='<div class="alert slert-danger">Error in updating</div>';
                }



                //get the all settings from database and store it to variable
                $data['site'] = $this->settings_model->SiteSettings(); 


                $this->load->view("layout/header",$data);
                $this->load->view("admineditaccount",$data);
                $this->load->view("layout/footer",$data);

            }
        }else
        {
            //get the all settings from database and store it to variable
            $data['site'] = $this->settings_model->SiteSettings(); 


            $this->load->view("layout/header",$data);
            $this->load->view("admineditaccount",$data);
            $this->load->view("layout/footer",$data);
        }

    }


    //Admin email check
    public function _checkMail($mail){

        $this->db->where('email', $mail);
        $query = $this->db->get('user');


        if($query->num_rows()==1){

            $this->form_validation->set_message('_checkMail', 'The email address already exist.');
            return FALSE;
        }
        else
        {
            return TRUE;
        }
    }

}

但问题是，当用户刚刚更改用户名时，会发生验证错误，因为我已经在表单上设置了字段的值

<div class="form-group">
    <label class="control-label col-xs-12 col-md-3" for="admin-email">Email :</label>
    <div class="col-xs-4">
        <input class="form-control" id="admin-email" name="admin-email" type="email" value="<?php echo $this->session->userdata['email']; ?>" 1required/>
        <?php echo form_error('admin-email'); ?>
    </div>
</div>

电邮：
我个人不会将post数据放在变量中，因为它已经是（个人预引用），除此之外，您希望检查每个可能更新的字段是否有值，执行如下操作：

 $data = array();
 if(!empty($this->input->post('username'))){
       $data['username'] = $this->input->post('username');
 }

并对您的每个输入重复此步骤。在那之后，它和你已经拥有的一样

 $this->db->where('id',$this->sessiondata['uid']);
 $this->db->update("table", $data);

当将value=”“设置为电子邮件或其他字段时如何<代码>！空（$this->input->post（'username'））

将始终为false。您的意思是在出现问题时提醒post数据？您不会使用会话，因为它不是写在您的会话中，而是写在您的帖子中，请使用value=”

 $this->db->where('id',$this->sessiondata['uid']);
 $this->db->update("table", $data);