Codeigniter：如何檢查MySQL數據庫中的用戶名是否已經存在

Question

我目前正在從事Codeigniter。 我不是使用框架的專家。 我有一個雇員的登記表，我希望它顯示“ 用戶名已存在 ” 用戶名輸入旁邊后，我提交按鈕。

這是mysql數據庫表的圖像：

mysql數據庫表的圖像

這是控制器（home.php）：

public function viewAddEmployeeForm() { 
        $this->load->model('Model_home');
        $data = array();
        $data['dropdown'] = $this->Model_home->get_dropdown();
        $this->load->view('imports/header');
        $this->load->view('imports/menu');
        $this->load->view('emp_add', $data);
    }

public function saveEmployee() {
        $this->load->model('Model_home');
        $p = new Model_home();
        $p->date_employed = $this->input->post('date_emp');
        $p->designation_id = $this->input->post('emp_desi');
        $p->username = $this->input->post('username');
        $p->password = $this->input->post('pswrd');
        $p->name = $this->input->post('emp_name');
        $p->midname = $this->input->post('emp_mname');
        $p->lastname = $this->input->post('emp_lname');
        $p->CityAddress = $this->input->post('emp_cadd');
        $p->license_num = $this->input->post('emp_license');
        $p->TIN_num = $this->input->post('emp_tin');
        $p->SSSNo = $this->input->post('emp_sss');
        $p->PhilHealth = $this->input->post('emp_ph');
        $p->DoB = $this->input->post('emp_dob');
        $p->Gender = $this->input->post('emp_gender');
        $p->contnum = $this->input->post('emp_mobno');
        $p->ContactPerson = $this->input->post('emp_contpers');
        $p->ContactPerson_Num = $this->input->post('emp_contpersnum');
        $p->ContactPerson_Add = $this->input->post('emp_contpersadd');

        if($p->designation_id == 1){
            $p->user_type = 0;
        }else{
            $p->user_type = 1;
        }
        $result = $p->saveEmployee();
        if (!$result) {
            echo mysqli_error($result);
        }
        else {
           redirect('home/goSettings', 'refresh');
        }
    }

這是視圖：（emp_add.php）：

<h1>Add Employee</h1>
<br>
<?php echo form_open('home/saveEmployee',array('class'=>'form-horizontal'));?>

<h4> Personal Information </h4>
<div class="form-group">
    <label class="control-label col-md-3 col-sm-3 col-xs-12" for="first-name">First Name <span class="required">*</span>
    </label>
    <div class="col-md-6 col-sm-6 col-xs-12">
        <input type="text" id="emp_name" name="emp_name" required="required" class="form-control col-md-7 col-xs-12">
    </div>
</div>
<div class="form-group">
    <label class="control-label col-md-3 col-sm-3 col-xs-12" for="last-name">Last Name <span class="required">*</span>
    </label>
    <div class="col-md-6 col-sm-6 col-xs-12">
        <input type="text" id="emp_lname" name="emp_lname" required="required" class="form-control col-md-7 col-xs-12">
    </div>
</div>
<div class="form-group">
    <label for="middle-name" class="control-label col-md-3 col-sm-3 col-xs-12">Middle Name / Initial</label>
    <div class="col-md-6 col-sm-6 col-xs-12">
        <input id="emp_mname" name="emp_mname" class="optional form-control col-md-7 col-xs-12" type="text">
    </div>
</div>
<div class="form-group">
    <label class="control-label col-md-3 col-sm-3 col-xs-12">Gender</label>
    <div class="col-md-6 col-sm-6 col-xs-12">
        <div id="gender" class="btn-group" data-toggle="buttons">
            <select id="emp_gender" name="emp_gender" class="form-control">
                <option id="emp_gender" name="emp_gender" value="Male">Male</option>
                <option id="emp_gender" name="emp_gender" value="Female">Female</option>
            </select>
        </div>
    </div>
</div>
<div class="form-group">
    <label class="control-label col-md-3 col-sm-3 col-xs-12">Date Of Birth <span class="required">*</span>
    </label>
    <div class="col-md-6 col-sm-6 col-xs-12">
        <input id="emp_dob" name="emp_dob" class="date-picker form-control col-md-7 col-xs-12" required="required" type="date">
    </div>
</div>
<div class="form-group">
    <label class="control-label col-md-3 col-sm-3 col-xs-12">Address <span class="required">*</span>
    </label>
    <div class="col-md-6 col-sm-6 col-xs-12">
        <input id="emp_cadd" name="emp_cadd" class="form-control col-md-7 col-xs-12" required="required" type="text">
    </div>
</div>
<h4> Employee Identification </h4>
<div class="form-group">
    <label class="control-label col-md-3 col-sm-3 col-xs-12">License Number</label>
    <div class="col-md-6 col-sm-6 col-xs-12">
        <input type="text" id="emp_license" name="emp_license" class="optional form-control">
    </div>
</div>
<div class="form-group">
    <label class="control-label col-md-3 col-sm-3 col-xs-12">TIN Number</label>
    <div class="col-md-6 col-sm-6 col-xs-12">
        <input type="text" id="emp_tin" name="emp_tin" class="optional form-control">
    </div>
</div>
<div class="form-group">
    <label class="control-label col-md-3 col-sm-3 col-xs-12">SSS Number</label>
    <div class="col-md-6 col-sm-6 col-xs-12">
        <input type="text" id="emp_sss" name="emp_sss" class="optional form-control" >
    </div>
</div>
<div class="form-group">
    <label class="control-label col-md-3 col-sm-3 col-xs-12">PhilHealth</label>
    <div class="col-md-6 col-sm-6 col-xs-12">
        <input type="text" id="emp_ph" name="emp_ph" class="optional form-control" >
    </div>
</div>
<div class="form-group">
    <label class="control-label col-md-3 col-sm-3 col-xs-12">Username <span class="required">*</span>
    </label>
    <div class="col-md-6 col-sm-6 col-xs-12">
        <input type="text" id="username" name="username" required="required" class="form-control col-md-7 col-xs-12" onblur="return check_username();">
        <div id="Info"></div>
    </div>
</div>
<div class="form-group">
    <label class="control-label col-md-3 col-sm-3 col-xs-12">Password <span class="required">*</span>
    </label>
    <div class="col-md-6 col-sm-6 col-xs-12">
        <input type="password" id="pswrd" name="pswrd" required="required" class="form-control col-md-7 col-xs-12">
    </div>
</div>
<h4> Work details </h4>   
<div class="form-group">
    <label class="control-label col-md-3 col-sm-3 col-xs-12">Date Employed <span class="required">*</span>
    </label>
    <div class="col-md-6 col-sm-6 col-xs-12">
        <input id="date_emp" name="date_emp" class="date-picker form-control col-md-7 col-xs-12" required="required" type="date">
    </div>
</div>
<div class="form-group">
    <label class="control-label col-md-3 col-sm-3 col-xs-12">Designation <span class="required">*</span>
    </label>
    <div class="col-md-6 col-sm-6 col-xs-12">

        <?php echo form_dropdown('emp_desi', $dropdown, '', 'class="form-control" id="emp_desi"'); ?>   

    </div>
</div>
<h4> Contact Information </h4>  
<div class="form-group">
    <label class="control-label col-md-3 col-sm-3 col-xs-12">Mobile Number <span class="required">*</span></label>
    <div class="col-md-6 col-sm-6 col-xs-12">
        <input type="text" id="emp_mobno" name="emp_mobno" class="form-control" required="required" >
    </div>
</div>
<h4> Contact Person </h4>
<div class="form-group">
    <label class="control-label col-md-3 col-sm-3 col-xs-12">Name <span class="required">*</span>
    </label>
    <div class="col-md-6 col-sm-6 col-xs-12">
        <input type="text" id="emp_contpers" name="emp_contpers" required="required" class="form-control col-md-7 col-xs-12">
    </div>
</div>
<div class="form-group">
    <label class="control-label col-md-3 col-sm-3 col-xs-12">Address <span class="required">*</span>
    </label>
    <div class="col-md-6 col-sm-6 col-xs-12">
        <input type="text" id="emp_contpersadd" name="emp_contpersadd" required="required" class="form-control col-md-7 col-xs-12">
    </div>
</div>
<div class="form-group">
    <label class="control-label col-md-3 col-sm-3 col-xs-12">Mobile Number <span class="required">*</span></label>
    <div class="col-md-6 col-sm-6 col-xs-12">
        <input type="text" id="emp_contpersnum" name="emp_contpersnum" required="required" class="form-control" >
    </div>
</div>                                  
<div class="ln_solid"></div>
<div class="form-group">
    <div class="col-md-6 col-sm-6 col-xs-12 col-md-offset-3">
        <button type="submit" class="btn btn-success" name="emp_submit" id="emp_submit" onclick="alert('You have successfully added an employee')">Submit</button>
    </div>
</div>

</form>

這是模型（model_home.php）：

public function saveEmployee() {
        if (isset($this->empnum)) {
            $query = $this->updateEmployee();
        }
        else {
            $query = $this->addEmployee();
        }

        return $query;
    }

public function get_dropdown() {
    $result = $this->db->select('designation_id, designation')->get('designation')->result_array();
    $dropdown = array();
    foreach($result as $r) {
        $dropdown[$r['designation_id']] = $r['designation'];
    }
    return $dropdown;
}

Answer 1

嘗試這個

$this->form_validation->set_rules('username', 'Username', 'required|is_unique[users.username]');

這里is_unique[users.username] ， users引用用戶表， username引用用戶表中的字段名。 這將自動檢查用戶表中的用戶名。

Answer 2

要查看數據庫中是否已經存在某些內容，通常可以使用LIKE命令或REGEXP命令來測試條目是否已經存在。 有關如何使用REGEXP的信息，請參閱本文：

where子句中的MySQL正則表達式

如果該物品已經存在，它將返回該物品。 如果不是，則應返回NULL或什么都不返回。

然后，您要做的就是刷新預先存在的HTML網頁。 您當前網頁中唯一需要的更改是一些PHP代碼，它們僅會回顯返回的信息。 所以簡單的東西像：

<?php echo $foundIt; ?>

將其放在用戶名（或顯示用戶名）的旁邊。 如果未找到任何內容，請確保使用空白字段聲明變量。 IE瀏覽器：

$foundIt = "";

否則，您的網頁將生成一條錯誤消息，指出它未定義。

我看到sriAnkush回答了您的問題。 我的答案是使用純HTML。 看起來他正在使用CodeIgniter。 :-)

Answer 3

嘗試像這樣的控制器功能。 在$username獲取Username並將其傳遞給模型。 使用Select查詢，其中username等於$username並返回數組。 如果有任何類似的用戶名， $result將大於或等於1，因此它將顯示用戶名已存在，否則將保存您的數據。

public function saveEmployee() {
  $username=$this->input->post('username');
  $result=$this->model->checkUsername($username);

  if($result>=1){
        echo "Username Already exists";
    }
  else{
      // Query to save the username and data;         
    }
}

祝好運！