php判断某个数组是否存在特定的键

               $result= $this->db->query("select  * from `qx`  where 1 limit 0,1")->result_array();  

               print_r($result[0]);

               echo "8888";
               if(array_key_exists(‘houtai‘, $result[0])){
                   echo "存在";
               }else{
                   echo "不存在";
               }
               echo  "9999";