php - Using Prepare and bind statement try to get JSON data type data from column but it return all column values '0' -

i using mysql 5.7 json properties. added 1 column json datatype. @ time of insertion values added in table prepare,bind mysql statement when try retrieve values json column return 0 values.

//insert

$state_head json associative array [{"state_id":"1","head_id":["1","4"]},{"state_id":"2","head_id":["2"]}] target number  $state_head=json_decode($state_head_data,true); for($i=0;$i<count($state_head);$i++) {     $stmt = $this->conn->prepare("insert ad_target_network(target_id,state_id,head) values(?,?,?)");     $stmt->bind_param("iis", $target_id,$state_head[$i]["state_id"],json_encode($state_head[$i]['head_id']));     $result=$stmt->execute();     $stmt->close();  } 

//select

$state_head=json_decode($state_head_data,true); for($i=0;$i<count($state_head);$i++) {      $stmt_select = $this->conn->prepare("select target_network_id,target_id,state_id,head ad_target_network target_id = ? , state_id=?");      $stmt_select->bind_param("ii",$target_id,$state_head[$i]["state_id"]);      $stmt_select->bind_result($target_network_id,$target,$state_id,$head);      $stmt_select->execute();      $stmt_select->store_result();      if($stmt_select->num_rows > 0)      {           while($stmt_select->fetch())          {                    array_push($data,array('target_network_id'=>$target_network_id,'target_id'=>$target,'state_id'=>$state_id,'head'=>$head));          }          $response[0] = 1;          $response[1] = $data;     }     $stmt_select->close(); } 

please me solve problem...i dont know why can not work.. return column value 0 & null below

//output

{   "target_network_id": 0,   "target_id": 0,   "state_id": 0,   "headend": null }, {   "target_network_id": 0,   "target_id": 0,   "state_id": 0,   "headend": null } 

but when remove 'head' column $this->conn->prepare(select) & other function bind result & array return ..

{   "target_network_id": 1,   "target_id": 2,   "state_id": 4, }, {   "target_network_id": 2,   "target_id": 2   "state_id": 6, }