PHP：致命错误：未捕获的 PDOException：SQLSTATE[HY000]

Question

I have a class named player that creates, deletes and controls if a player entity exists. In another file, I have the database connection with PDO and, finally, in third file I have the call to player class. Here's all the code:

file: player.php

<?php
    class player
    {
        private $pdo;
        private $network_id;
        public $color;

        public function __construct($pdo, $network_id, $color)
        {
            $this->pdo = $pdo;
            $this->network_id = $network_id;
            $this->color = $color;
        }

        public function create_player()
        {
            if(!$this->exists_player())
            {
                $sql = 'INSERT INTO players SET network_id = :network_id';
                $query = $this->pdo->prepare($sql);
                $query->execute(array(':network_id' => $this->network_id));
            }
            else
            {
                echo 'error';
            }
        }

        public function delete_player()
        {
            if($this->exists_player())
            {
                $sql = 'DELETE FROM players WHERE network_id = :network_id';
                $query = $this->pdo->prepare($sql);
                $query->execute(array(':network_id' => $this->network_id));
            }
            else
            {
                return -1;
            }
        }

        private function exists_player()
        {
            $sql = 'SELECT COUNT(*) FROM players WHERE network_id = '.$this->network_id;
            $result = $this->pdo->exec($sql);

            if($result > 0) return true;
            else return false;
        }
    }
?>

file: test.php

<?php
   include './Php/db_connection.php';
   include './Php/player.php';

    $player = new player($pdo, 1112, 'red');

    $player->create_player();
?>

file: db_connection.php

 $pdo = new PDO('mysql:host=localhost; dbname=myDbName', 'dbUtent', 'myPassword');
 $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);    

The thing is that when I call test.php , I get this error:

Fatal error: Uncaught PDOException: SQLSTATE[HY000]: General error: 2014 Cannot execute queries while other unbuffered queries are active. Consider using PDOStatement::fetchAll(). Alternatively, if your code is only ever going to run against mysql, you may enable query buffering by setting the PDO::MYSQL_ATTR_USE_BUFFERED_QUERY attribute. in F:\\Software\\Coding_Development_Software\\Server\\wamp\\www\\myProject\\Ajax\\Cube\\Php\\player.php on line 21

All code is an exemple.

Any ideas?

Answer 1

The thing here is that you need to fetch until it fails for a row fetch attempt. In fact, your own exception is telling you the solution:

Consider using PDOStatement::fetchAll(). Alternatively, if your code is only ever going to run against mysql, you may enable query buffering by setting the PDO::MYSQL_ATTR_USE_BUFFERED_QUERY attribute. in F:\\Software\\Coding_Development_Software\\Server\\wamp\\www\\myProject\\Ajax\\Cube\\Php\\player.php on line 21