PDO implements a method to determine whether the connection is available-PHP Tutorial-php.cn

This article mainly introduces the method of php PDO to determine whether the connection is available. Interested friends can refer to it. I hope it will be helpful to everyone.

mysql_ping() Checks whether the connection to the server is normal. Returns true if a connection to the server is available, false otherwise.

But PDO does not support themysql_ping()method, so you need to write your own code to simulate the mysql_ping() method to check whether the connection is available.

The code is as follows:

getAttribute(PDO::ATTR_SERVER_INFO); } catch (PDOException $e) { if(strpos($e->getMessage(), 'MySQL server has gone away')!==false){ return false; } } return true; } ?>

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Code demonstration:

1. Create a test data table

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

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2. Insert test data

insert into user(name) values('fdipzone'),('xfdipzone'),('terry'); mysql> select * from user; +----+-----------+ | id | name | +----+-----------+ | 1 | fdipzone | | 2 | xfdipzone | | 3 | terry | +----+-----------+

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3. Demo file

db.php

 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; } } ?>

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test.php

 'localhost', 'dbname' => 'user', 'user' => 'root', 'password' => '', 'pconnect' => 0, 'charset' => '' ); // 循环执行 while(true){ // 创建数据连接 $dbconn = DB::get_conn($config); // 判断连接是否有效 $status = pdo_ping($dbconn); if($status){ echo 'connect ok'.PHP_EOL; }else{ echo 'connect failure'.PHP_EOL; // 重置连接 DB::reset_connect(); $dbconn = DB::get_conn($config); } // 执行查询 $sqlstr = 'select * from user where id=?'; $condparam = array(mt_rand(1,3)); $data = DB::query($dbconn, $sqlstr, $condparam); print_r($data); // 延时10秒 echo 'sleep 10'.PHP_EOL.PHP_EOL; sleep(10); } /** * 检查连接是否可用 * @param Link $dbconn 数据库连接 * @return Boolean */ function pdo_ping($dbconn){ try{ $dbconn->getAttribute(PDO::ATTR_SERVER_INFO); } catch (PDOException $e) { if(strpos($e->getMessage(), 'MySQL server has gone away')!==false){ return false; } } return true; } ?>

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4. Execution

Execute test.php in php cli mode, and then immediately execute mysql.server stop and mysql.server start to simulate a flash interruption

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

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Execution output:

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

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You can see that after the interruption, pdo_ping() returns false and the connection fails. Then call automatic reconnection to ensure that subsequent queries can continue to be executed.

The above is the entire content of this article, I hope it will be helpful to everyone's study.

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