希望这能帮助您：
更改您的模型如下：

function getCitybyId($city)
{
    $this->db->select('cityName');
    $this->db->from('city');
    $this->db->where("city_id", $city);
    $query = $this->db->get();
    if ($query->num_rows() > 0 )
    {
       return $query->row()->cityName;
    }

}

在控制器中

$data['jobCityName'] = explode(',',$viewData['jobCity']);
foreach($data['jobCityName'] as $cityid) {        
    /*$data['jobCityNames']=$this->hrm_model->getCitybyId($cityid);*/
    $data['jobCity'][] = $this->hrm_model->getCitybyId($cityid);
}
$data['jobCity'] = implode(',',$data['jobCity']);

对于单个城市，请使用：

$data['single_city_name'] = $this->hrm_model->getCitybyId($cityid);

将其传递给视图：

$this->load->view('your_view',$data);

使用result_array（）函数返回多个值

return $query->result_array();

如果你想展示金奈、海得拉巴、孟买等城市，试试这个。

<?php echo $jobCity.","; ?>

除第一项外，在此处加逗号：

$data['jobCityName'] =explode(',',$viewData['jobCity']);
$isFirst = true;
foreach($data['jobCityName'] as $cityid) {        
    $data['jobCityNames']=$this->hrm_model->getCitybyId($cityid);
    $data['jobCity'].=$data['jobCityNames']['cityName'].($isFirst ? "" : ",");
    $isFirst = false;
}