mysql_ping

(PHP 4 >= 4.3.0, PHP 5)

mysql_pingPinga uma conexão com o servidor ou reconecta se não houver conexão

Aviso

Esta extensão tornou-se defasada a partir do PHP 5.5.0 e foi removida no PHP 7.0.0. Em vez disso, as extensões MySQLi ou PDO_MySQL devem ser usadas. Veja também o guia MySQL: escolhendo uma API. Alternativas a esta função incluem:

Descrição

mysql_ping(resource $link_identifier = NULL): bool

Confere se a conexão com o servidor está funcionando ou não. Se ela tiver caído, tenta realizar uma conexão automática. Esta função pode ser usada em scripts que permanecem inativos por um longo tempo, para verificar se o servidor fechou ou não a conexão e reconectar se necessário.

Nota:

A reconexão automática está desabilitada por padrão em versões do Mysql >= 5.0.3.

Parâmetros

link_identifier

A conexão MySQL. Se o identificador da conexão não for especificado, a última conexão aberta por mysql_connect() será usada. Se não houver uma conexão anterior, haverá uma tentativa de criar uma como se mysql_connect() tivesse sido chamada sem argumentos. Se nenhuma conexão for encontrada ou estabelecida, um erro de nível E_WARNING será gerado.

Valor Retornado

Retorna true se a conexão com o servidor MySQL está funcionando, se não retorna false.

Exemplos

Exemplo #1 Exemplo mysql_ping()

<?php
set_time_limit
(0);

$conn = mysql_connect('localhost', 'mysqluser', 'mypass');
$db = mysql_select_db('mydb');

/* Assuming this query will take a long time */
$result = mysql_query($sql);
if (!
$result) {
echo
'Query #1 failed, exiting.';
exit;
}

/* Make sure the connection is still alive, if not, try to reconnect */
if (!mysql_ping($conn)) {
echo
'Lost connection, exiting after query #1';
exit;
}
mysql_free_result($result);

/* So the connection is still alive, let's run another query */
$result2 = mysql_query($sql2);
?>

Veja Também

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User Contributed Notes 7 notes

up
3
cybot2000 at yahoo dot de
18 years ago
It should be noted that mysql_ping() seems to reset the error message on the server.
I used it to check whether the connection was still alive before reading the error message via mysql_error() and it always returned an empty string. Upon removing the connection check everything worked.
up
3
alext at marketdream dot com dot mx
14 years ago
mysql_ping() is really helpful when you have this annoying error:

MYSQL Error 2006 Server has gone away

For CI users:
In 1.7.2 version of codeigniter, there is a function

$this->db->reconnect()

that uses mysql_ping() to reestablish the timed out connection.

This function is specially useful when developing social media sites that uses hundreds of connections to the db such asinserting or selecting.
up
2
dustin hawkins
17 years ago
When using the mysql_ping command under php 5.1.2 and mysql 5.0, I was having problems with the auto-reconnect "feature", mainly that when the connection was severed, a mysql_ping would not automatically re-establish the connection to the database.

The connection to the DB is dropped when the time without a query excedes the wait_timeout value in my.cnf. You can check your wait_timeout by running the query "SHOW VARIABLES;"

If you're having problems auto-reconnecting when the connection is dropped, use this code:

<?php

$conn
= mysql_connect('localhost','user','pass');
mysql_select_db('db',$conn);

if (!
mysql_ping ($conn)) {
  
//here is the major trick, you have to close the connection (even though its not currently working) for it to recreate properly.
  
mysql_close($conn);
  
$conn = mysql_connect('localhost','user','pass');
  
mysql_select_db('db',$conn);
}

//run queries knowing that your connection is alive....

?>
up
1
miro dot dietiker at md-systems dot ch
16 years ago
When checking if a $resource works...
be prepared that mysql_ping returns NULL as long as $resource is no correct mysql resource.
<?php
$resource
=NULL;
var_dump = @mysql_ping($resource);
# showing NULL
?>
This could be used to decide of a current $resource is a mysql or a mysqli connection when nothing else is available to do that...
up
1
Doug
13 years ago
This function *does not* attempt to reconnect at this time.  It only tells you whether or not you currently *are* connected.

To actually reconnect, you will have to implement this yourself in a wrapper class.
up
1
vinicius at teracom dot com dot br
20 years ago
Is important to remember that if your first connection to mysql don't works, mysql_ping will always return true! So, if you want to check if mysql is connected, first of all you must check if mysql_connect do not returns false and then you can begin to check mysql_ping.
up
-4
luky37
15 years ago
If you get 'error 2006: MySQL server has gone away' messages when running (really) long scripts, mysql_ping will help detecting the loss of the db-connection. This can happen, when 'wait timeout' is reached (MySQL default is 8 hours).
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