mysql_client_encoding
A little note about multiple simultaneous connections to different hosts...
I work on a site that pulls content primarily from one db but uses a db on a foreign server to verify licensing. One might expect the following to work:
<?php
// Open the connection to the primary db
$res1 = mysql_connect($host1, $user1, $pass1);
mysql_select_db($db1);
// Open connection to the license server
$res2 = mysql_connect($host2, $user2, $pass2);
mysql_select_db($db2, $res2);
// Pull license data and close when done
mysql_query($check_sql, $res2);
// ...
mysql_close($res2);
// Now pull content from the primary db
// Not specifying the resource should default to the last open db
mysql_query($query);
// ...
?>
Turns out this last query, since it cant find an active connection, will try to connect with mysql_connect() with no paramaters. But if instead you do it as mysql_query($query, $res1), or alternatively, run the mysql_connect for this host again then it works fine. Thus, it doesnt seem to be possible to have code with an overarching "global" db connection interspersed with temporary connections to another host/db....
mysql_close
(PHP 4, PHP 5, PECL mysql:1.0)
mysql_close — Chiude una connessione MySQL
Descrizione
bool mysql_close
([ resource $
identificativo_connessione
] )
Restituisce TRUE in caso di successo, FALSE in caso di fallimento.
mysql_close() chiude la connessione al server MySQL associata all'identificativo di connessione specificato. Se identificativo_connessione non è specificato, viene usata l'ultima connessione aperta.
L'uso di mysql_close() non è normalmente necessario, dal momento che le connessioni non persistenti sono chiuse automaticamente alla fine dell'esecuzione dello script. Vedere anche freeing resources.
Nota: mysql_close() non chiude le connessioni persistenti create da mysql_pconnect().
Example #1 Esempio di chiura connessione MySQL
<?php
$connessione = mysql_connect("localhost", "utente_mysql", "password_mysql")
or die("Connessione non riuscita: " . mysql_error());
print ("Connesso con successo");
mysql_close($connessione);
?>
Vedere anche: mysql_connect(), e mysql_pconnect().
add a note
User Contributed Notesmysql_close
bbodelcampo at yahoo dot co dot uk
13-Dec-2005 01:20
13-Dec-2005 01:20
levi at alliancesoftware dot com dot au
29-Apr-2005 07:03
29-Apr-2005 07:03
As at 5.0.x and 4.3.x: This function should never be used with shared links; instead you should set your link variables to null.
(This explains red's and beer's () problems in previous comments)
Here is how shared links work:
- Each link is a resource. mysql_connect() by default looks for a resource with the same paramaters. If one exists, it will return the existing resource.
- Every assignment of that resource to a variable increases the resource's reference count.
- When the reference is decremented to zero, the underlying TCP/socket connection is closed.
- Every assignment of a variable away from that resource decrements the reference count. (This includes a function level variable going out of scope)
- mysql_close() also decrements the reference count.
Note the last two points: mysql_close() _and_ reassignment of a variable decrement the link's reference count.
A common mistake is a function like:
<?php
function dothings() {
$link = mysql_open(...);
// .. do some queries ..
mysql_close($link)
$link = null;
}
?>
this will decrement the counter twice, possibly closing the underlying connection and causing errors in other parts of the program.
http://bugs.php.net/bug.php?id=30525 "this is not a bug but just how it works"
beer_nomaed _AT_ hotmail _DOT_ com
03-Dec-2004 09:26
03-Dec-2004 09:26
Be careful when using multiple links to connect to same database (with same username). Unless you specify explicitly in mysql_connect() to create a new link, it will return an already open link. If that would be closed by mysql_close(), it will also (obviously) close the other connection, since the link is the same.
Had lot of trouble figuring it out, since in <=4.3.6 there was a bug which didn't close the connection, but after the patch to >=4.3.7, all my application broke down because of a single script that did this.