mysql_ping

(PHP 4 >= 4.3.0, PHP 5)

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

Descrição

bool mysql_ping ([ resource $link_identifier ] )

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

Nota:

Desde o MySQL 5.0.13, o recurso de automática reconexão está desabilitada.

Parâmetros

link_identifier

The MySQL connection. If the link identifier is not specified, the last link opened by mysql_connect() is assumed. If no such link is found, it will try to create one as if mysql_connect() was called with no arguments. If no connection is found or established, an E_WARNING level error is generated.

Valor Retornado

Retorna TRUE se a conexão com o servidor MySQL esta 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
1
Doug
4 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
alext at marketdream dot com dot mx
4 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
0
luky37
5 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).
up
0
miro dot dietiker at md-systems dot ch
6 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
0
dustin hawkins
7 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
0
cybot2000 at yahoo dot de
8 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
0
vinicius at teracom dot com dot br
10 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.
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