Codeigniter：如何检查MySQL数据库中的用户名是否已经存在

Question

I'm currently working on codeigniter. I am not so expert using framework. I have a registration form of an employee and I want it to display " username already exists " beside the Username input after I submit a button.

Here is the image of tables from mysql database:

Image of tables from mysql database

Here is the controller (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');
        }
    }

Here is the view: (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>

Here is the model (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

Try this

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

Here is_unique[users.username] , users refer to users table & username refer to field name in users table. This will automatically check for username in users table.

Answer 2

To see if something already exists in a database you usually either use the LIKE command or a REGEXP command to test if the entry is already there. See this article for how to use REGEXP:

mySQL regex in the where clause

If the item is already there it will return the item. If not it should return NULL or nothing.

Then all you do is to refresh the pre-existing HTML web page. The only change you need in your current web page is a bit of PHP code that just echos the returning information. So something simple like:

<?php echo $foundIt; ?>

You put that next to where they put in the username (or the username is displayed). Be sure to declare the variable with a blank field if nothing is found. IE:

$foundIt = "";

Otherwise your web page will generate an error saying it is undefined.

I see sriAnkush answered your question. My answer is using plain HTML. Looks like his is using CodeIgniter. :-)

Answer 3

try controller function like this. Get Username in $username and pass it to model. use Select query where username is equal to $username and return the array. If there is any similar username $result will be greater than or equal to 1. so it will show username already exist else it will save your data.

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;         
    }
}

Good Luck!