mysql_ping

(PHP 4 >= 4.3.0, PHP 5)

mysql_pingVérifie la connexion au serveur MySQL, et s'y reconnecte au besoin

Avertissement

Cette extension était obsolète en PHP 5.5.0, et a été supprimée en PHP 7.0.0. À la place, vous pouvez utiliser l'extension MySQLi ou l'extension PDO_MySQL. Voir aussi MySQL : choisir une API du guide. Alternatives à cette fonction :

Description

mysql_ping(resource $link_identifier = NULL): bool

mysql_ping() vérifie si la connexion au serveur link_identifier fonctionne. Si elle est tombée, une reconnexion automatique est effectuée. Cette fonction est utile pour les scripts qui restent inactifs durant un long moment. Ils peuvent ainsi vérifier si le serveur a fermé la connexion, pour cause d'inactivité.

Note:

La reconnexion automatique est désactivée par défaut depuis la version 5.0.3 et suivants de MySQL.

Liste de paramètres

link_identifier

La connexion MySQL. S'il n'est pas spécifié, la dernière connexion ouverte avec la fonction mysql_connect() sera utilisée. Si une telle connexion n'est pas trouvée, la fonction tentera d'ouvrir une connexion, comme si la fonction mysql_connect() avait été appelée sans argument. Si aucune connexion n'est trouvée ou établie, une alerte de niveau E_WARNING sera générée.

Valeurs de retour

Retourne true si la connexion au serveur MySQL fonctionne, false sinon.

Exemples

Exemple #1 Exemple avec mysql_ping()

<?php
set_time_limit
(0);

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

/* En supposant que l'exécution de la requête prend beaucoup de temps */
$result = mysql_query($sql);
if (!
$result) {
echo
'Requête #1 a échoué, sortie.';
exit;
}

/* S'assure que la connexion est toujours active, sinon, tentative de reconnexion */
if (!mysql_ping($conn)) {
echo
'Perte de la connexion, sortie après la requête #1';
exit;
}
mysql_free_result($result);

/* Donc, la connexion est toujours active, exécutons une autre requête */
$result2 = mysql_query($sql2);
?>

Voir aussi

add a note

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
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
2
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
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
2
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
-3
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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