Question

如何在null查询中取0值而不是$get参数，其中persent是alise。请回答这个问题。

这是显示所有数据的api函数。

 public function get_vote_list($parameter) {

            $data_available = "0";
            $access_token = $parameter->token;
            $type = $parameter->election_type;
            $limit = $parameter->limit;
            $offset =  $parameter->page;      
            $offset = $limit * $offset; 
            $test=null;

             $check_feature_type = $this->common->get_feature_type('Election');
             $check_total_hospitals = $this->common->get_count_election();
            $user_id = $this->common->get_access_token_id($access_token);
                if ($check_total_hospitals > 0) {
                $reset_read_count = "update tbl_feature_read_count set read_count = '0', modified_date =now() where user_id = '$user_id' and feature_id = '".$check_feature_type->feature_id."'";
                $this->db->query($reset_read_count);
            }

            $type_where = " ";
            switch ($type) {
                    case "mla": $type_where = " where election_type='1' ";

                    break;

                    case "nagarsevak": $type_where = " where election_type='2' ";

                    break; 
                default:

                    $type_where = " where election_type in ('1','2') ";               
                    break;        
            }
            $where_election_type_id = " where election_type='".$type."' ";

     $get = "SELECT id,candidate_name,image,electionDate,election_type,education,description,ward,election_name,location,FROM_UNIXTIME(createdOn, '%e %b %Y') as createdOn ,(SELECT COUNT(id) AS `count` FROM tbl_election_support where election_id =tbl_elections.id) voteCount ,(select count(at.id) from tbl_elections as at where at.election_type=tbl_elections.election_type) as candidate_count,(SELECT COUNT(id) AS `count` FROM tbl_election_support where election_id in (select at.id from tbl_elections as at where at.election_type=tbl_elections.election_type)) total_vote_count,ROUND((SELECT COUNT(id) AS `count` FROM tbl_election_support where election_id =tbl_elections.id)/(SELECT COUNT(id) AS `count` FROM tbl_election_support where election_id in (select at.id from tbl_elections as at where at.election_type=tbl_elections.election_type))*100, 2) persent from tbl_elections $where_election_type_id
                            ORDER BY ward DESC";


      $word_get = " SELECT * from tbl_election_ward $where_election_type_id limit ".$offset.",".$limit."";
                       $list =  $this->db->query($get);
                       $list1 = $list->fetch_all(MYSQLI_ASSOC);
                       $test = NULL;

              $word_get1 = $this->db->query($word_get);
              $word_get2 = $word_get1->fetch_all(MYSQLI_ASSOC);

              foreach($list1 as $row){
                //-------start to fetch food total views
                $view_query="SELECT COUNT(user_id) AS support FROM tbl_election_support";
                $view_query_result=$this->db->query($view_query);
               $view_data = $view_query_result->fetch_assoc();                                    
             }

          foreach ($word_get2 as $key => $value) {
              $test[$value['id']]=$value;
          }

            foreach ($list1 as $key => $value) {
            //$test['ward'][$value['ward']]['wardlist'][]=$value;
            $test[$value['ward']]['wardlist'][]=$value;
            }

            $value1=null ;
        foreach ($word_get2 as $key => $value) {
              $value1[]=$test[$value['id']];
          }        
            $test=$value1;

      date_default_timezone_set("Asia/Kolkata");    
      return array("status" => TRUE, "message" => "success", "data" => $test, "extra_detail" => array("curdate" => date("d M Y"), "data_available" => $data_available));

        if($token != "0" && $data){
            return array("status" => TRUE, "message" => "success", "data" => $test, "extra_detail" => array("curdate" => date("d M Y"), "data_available" => $data_available));
          }  
          else
            if(!$data){
            return array("status" => TRUE, "message" => "No comments", "data" => $data, "extra_detail" => array("curdate" => date("d M Y"), "data_available" => $data_available));
          }  
          else

             {
            return array("status" => FALSE, "message" => "invalid token", "extra_detail" => array("curdate" => date("d M Y"), "data_available" => '0'));
          }  
            exit();
        }

Answer 1

使用** coalesce**函数来避免空值

SELECT id,candidate_name,image,electionDate,election_type,education,
           description,ward,election_name,location,FROM_UNIXTIME(createdOn, '%e %b %Y') as createdOn ,
           (SELECT COUNT(id) AS `count` 
            FROM tbl_election_support 
            where election_id =tbl_elections.id
           ) voteCount ,
           (select count(at.id) 
           from tbl_elections as at
           where at.election_type=tbl_elections.election_type
          ) as candidate_count,
          (SELECT COUNT(id) AS `count` 
           FROM tbl_election_support 
           where election_id in (select at.id 
                    from tbl_elections as at 
                                where at.election_type=tbl_elections.election_type
                                )
          ) total_vote_count,
          coalesce(ROUND(
                (SELECT COUNT(id) AS `count` 
                 FROM tbl_election_support 
                 where election_id =tbl_elections.id
                )/
                (SELECT COUNT(id) AS `count` 
                 FROM tbl_election_support 
                 where election_id in (select at.id 
                                       from tbl_elections as at 
                                       where at.election_type=tbl_elections.election_type
                                      )
                 )*100, 2
               ),0) persent 
    from tbl_elections 
    $where_election_type_id
    ORDER BY ward DESC;

使用php和Mysql显示0 insted NULL值？

1 个答案: