Jquery 根据第一个下拉列表填充下拉列表

我想在从“要去的部门”下拉框中选择一个部门后填充“要去的部门”下拉框，但当我单击“部门列表”时，所有部门都会显示，但当我选择一个部门时，该部门的相关员工不会显示在“要去的部门”下拉列表中。下面是我的两张桌子。 部门表

用户主表

我的控制器

我的看法

我的jquery

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在您的模型中，在“按类别选择项目”功能中

这是错误的$this->db->where'dept_id'，'category_id'

查询的执行方式如下

SELECT * FROM `user_master` WHERE `dept_id` = '$category_id'

所以把它改成

$this->db->where('dept_id', $category_id);

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尝试一下它可以帮助您：

您可以通过放置echo$this->db->last\u query来检查您的上一次查询；出口返回$query->result\u数组前；在将“$category\u id”更改为$category\u id后，在您的“选择项目\u by\u”目录中，工作正常，谢谢您的帮助。

public function create_pass() {
    $pageid = 1;
    $data['hh'] = $this->admin_model->get_dept();
    $this->load->view('header');
    $this->load->view('sidebar');
    $this->load->view('createpass', $data);
    $this->load->view('footer');
}   

public function select_item_by_dept() {
    if ($this->session->userdata('admin_logged_in')) {
        $category_id = $this->input->post('category_id');
        $data['result'] = $this->admin_model->select_item_by_cat($category_id);

        $HTML = "";            
        foreach ($data['result'] as $list) {
            $HTML.="<option value='" . $list['dept_id'] . "'>" . $list['emp_name'] . "</option>";
        }           
        echo $HTML;
    } else {
        $this->load->view('login');
    }
}

function select_item_by_cat($category_id) {
    $this->db->where('dept_id', '$category_id');
    $query = $this->db->get('user_master');
    return $query->result_array();
}
function get_dept() {
    $this->db->select("*");
    $this->db->from('department');
    $query = $this->db->get();
    return $query->result_array();
}

<div class="form-group">
  <label for="inputPassword3" class="col-sm-3 control-label">Department to go </label>
  <div class="col-sm-3">
    <select class="form-control select2" name="dptgo" id="dptogo" onchange="change_category(this.options[this.selectedIndex].value)" style="width: 100%;">
      <option selected="selected">Select</option>                                                    
      <?php foreach($hh as $datas)
      { ?>
        <option value="<?php echo $datas['id']; ?>"><?php echo $datas['dept_name']; ?></option>
<?php } ?>
    </select>
    <div class="text-danger"><?php echo form_error('dptgo'); ?></div>
  </div>
  <label for="inputPassword3" class="col-sm-2 control-label">Whom to Meet</label>
  <div class="col-sm-4">
    <select class="form-control select2" id="whomtmt" name="wtomeet" style="width: 100%;">
      <option selected="selected">Select</option>
      <option></option>
    </select>
  </div>
</div>

<script>
  function change_category(category_id) {
    if (category_id == "Select") {
      $("#whomtmt").html("<option>Select</option>");
      $("#whomtmt").trigger("chosen:updated");
      $("#whomtmt").trigger("liszt:updated");
    } else {
      loadData(category_id);
    }
  }
  function loadData(category_id) {
    var dataString = 'category_id=' + category_id;
    $.ajax({
      type: "POST",
      url: "<?php echo site_url(); ?>/admin/select_item_by_dept",
      data: dataString,
      cache: false,
      success: function (result) {
        $("#whomtmt").html("<option>Select</option>");
        $("#whomtmt").append(result);
        $("#whomtmt").trigger("chosen:updated");
        $("#whomtmt").trigger("liszt:updated");
      }
    });
  }
</script>

SELECT * FROM `user_master` WHERE `dept_id` = '$category_id'

$this->db->where('dept_id', $category_id);