<"color: #ff0000">1、创建测试数据表



CREATE TABLE `user` (
 `id` int(11) unsigned NOT NULL AUTO_INCREMENT,
 `name` varchar(20) NOT NULL,
 PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;





2、插入测试数据


insert into user(name) values('fdipzone'),('xfdipzone'),('terry');

mysql> select * from user;
+----+-----------+
| id | name   |
+----+-----------+
| 1 | fdipzone |
| 2 | xfdipzone |
| 3 | terry   |
+----+-----------+





3、演示文件
db.php


<"mysql:host=$dbhost;dbname=$dbname;";
    try {
      $h_param = array(
          PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION,
      );
      if ($charset != '') {
        $h_param[PDO::MYSQL_ATTR_INIT_COMMAND] = 'SET NAMES ' . $charset; //設置默認編碼
      }
      if ($pconnect) {
        $h_param[PDO::ATTR_PERSISTENT] = true;
      }
      $conn = new PDO($dsn, $dbuser, $dbpasswd, $h_param);

    } catch (PDOException $e) {
      throw new ErrorException('Unable to connect to db server. Error:' . $e->getMessage(), 31);
    }

    self::$_instance = $conn;
    return $conn;
  }

  // 执行查询
  public static function query($dbconn, $sqlstr, $condparam){
    $sth = $dbconn->prepare($sqlstr);
    try{
      $sth->execute($condparam);
    } catch (PDOException $e) {
      echo $e->getMessage().PHP_EOL;
    }
    $result = $sth->fetchAll(PDO::FETCH_ASSOC);
    return $result;
  }

  // 重置连接
  public static function reset_connect(){
    self::$_instance = null;
  }

}
"background-color: #ccffcc">test.php




<"background-color: #ccffcc">4、执行

在php cli模式下执行test.php，然后马上执行mysql.server stop 与 mysql.server start 模拟闪断


mysql.server stop
Shutting down MySQL
.... SUCCESS! 
mysql.server start
Starting MySQL
 SUCCESS! 





执行输出：


connect ok
Array
(
  [0] => Array
    (
      [id] => 2
      [name] => xfdipzone
    )

)
sleep 10

connect failure
Array
(
  [0] => Array
    (
      [id] => 3
      [name] => terry
    )

)
sleep 10

connect ok
Array
(
  [0] => Array
    (
      [id] => 3
      [name] => terry
    )

)
sleep 10




可以看到闪断后，pdo_ping()返回false，连接失败，然后调用自动重连，保证后面的查询能继续执行。
以上这篇php PDO判断连接是否可用的实现方法就是小编分享给大家的全部内容了，希望能给大家一个参考，也希望大家多多支持。

                                
                                

                                    pdo,判断连接是否可用 
                                
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