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(PHP 4, PHP 5)

mysql_closeЗакрывает соединение с сервером MySQL


bool mysql_close ([ resource $link_identifier ] )

Возвращает TRUE в случае успешного завершения или FALSE в случае возникновения ошибки.

mysql_close() закрывает соедиение с базой данных MySQL, на которое указывает переданный указатель. Если параметр link_identifier не указан, закрывается последнее открытое (текущее) соединение.

Использование mysql_close() не необходимо для непостоянных соединений. Они автоматически закрываются в конце скрипта. См. также высвобождение ресурсов.

Замечание: mysql_close() не может закрывать постоянные соединения, открытые функцией mysql_pconnect().

Пример #1 Пример использования

        or die(
"Could not connect: " mysql_error());
    print (
"Connected successfully");

См. также mysql_connect() и mysql_pconnect().

User Contributed Notes
23-Apr-2010 09:26
At least with PHP5.3.2 and Windows connecting by tcp, you should always use this mysql_close() function to close and free up the tcp socket being used by PHP.  Garbage collection after script execution does not close the tcp socket on its own.  The socket would otherwise remain in 'wait' state for approximately 30 seconds, and any additional page loads/connection attempts would only add to the total number of open tcp connections.  This wait time does not appear to be configurable via PHP settings.
agneady (nospam please) at gmail dot com
11-Oct-2009 09:09
It seems that as of PHP 5.3, the link_identifier parameter is no longer optional. If not included, it would cause the script to crash with no errors in the output.
bbodelcampo at yahoo dot co dot uk
13-Dec-2005 01:20
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:

// Open the connection to the primary db
$res1 = mysql_connect($host1, $user1, $pass1);

// 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);
// ...

// Now pull content from the primary db
// Not specifying the resource should default to the last open db
// ...

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....
levi at alliancesoftware dot com dot au
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:

function dothings() {
$link = mysql_open(...);
// .. do some queries ..
$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
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.

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