MySQL Functions (PDO_MYSQL)

Introduzione

PDO_MYSQL is a driver that implements the PHP Data Objects (PDO) interface to enable access from PHP to MySQL databases.

PDO_MYSQL uses emulated prepares by default.

MySQL 8

When running a PHP version before 7.1.16, or PHP 7.2 before 7.2.4, set MySQL 8 Server's default password plugin to mysql_native_password or else you will see errors similar to The server requested authentication method unknown to the client [caching_sha2_password] even when caching_sha2_password is not used.

This is because MySQL 8 defaults to caching_sha2_password, a plugin that is not recognized by the older PHP (mysqlnd) releases. Instead, change it by setting default_authentication_plugin=mysql_native_password in my.cnf. The caching_sha2_password plugin is fully supported as of PHP 7.4.4. For older releases, the mysql_xdevapi extension does support it.

Avviso

Beware: Some MySQL table types (storage engines) do not support transactions. When writing transactional database code using a table type that does not support transactions, MySQL will pretend that a transaction was initiated successfully. In addition, any DDL queries issued will implicitly commit any pending transactions.

Nota:
The MySQL driver does not properly support PDO::PARAM_INPUT_OUTPUT via PDOStatement::bindParam(); while such parameters can be used, they are not updated (i.e. the actual output is ignored).

Installazione

The common Unix distributions include binary versions of PHP that can be installed. Although these binary versions are typically built with support for the MySQL extensions, the extension libraries themselves may need to be installed using an additional package. Check the package manager that comes with your chosen distribution for availability.

For example, on Ubuntu the php5-mysql package installs the ext/mysql, ext/mysqli, and PDO_MYSQL PHP extensions. On CentOS, the php-mysql package also installs these three PHP extensions.

Alternatively, you can compile this extension yourself. Building PHP from source allows you to specify the MySQL extensions you want to use, as well as your choice of client library for each extension.

When compiling, use --with-pdo-mysql[=DIR] to install the PDO MySQL extension, where the optional [=DIR] is the MySQL base library. Mysqlnd is the default library. For details about choosing a library, see Choosing a MySQL library.

Optionally, the --with-mysql-sock[=DIR] sets to location to the MySQL unix socket pointer for all MySQL extensions, including PDO_MYSQL. If unspecified, the default locations are searched.

Optionally, the --with-zlib-dir[=DIR] is used to set the path to the libz install prefix.

$ ./configure --with-pdo-mysql --with-mysql-sock=/var/mysql/mysql.sock

SSL support is enabled using the appropriate PDO_MySQL constants, which is equivalent to calling the » MySQL C API function mysql_ssl_set(). Also, SSL cannot be enabled with PDO::setAttribute because the connection already exists. See also the MySQL documentation about » connecting to MySQL with SSL.

Costanti predefinite

Le costanti qui sotto sono definite da questo driver, e sono disponibili solo quanto l'estensione è stata o compilata nel PHP o caricata dinamicamente a runtime. In aggiunta, queste costanti specifiche del driver dovrebbero essere usate solo se si sta usando il driver stesso. Utilizzare attributi specifici di mysql con il driver postgres può portare a risultati imprevedibili. PDO::getAttribute() può essere usata per ottenere l'attributo PDO_ATTR_DRIVER_NAME per identificare il driver, se il codice può funzionare con driver differenti.

PDO::MYSQL_ATTR_USE_BUFFERED_QUERY (bool)

By default all statements are executed in buffered mode. If this attribute is set to false on a PDO object, the MySQL driver will use the unbuffered mode.

Example #1 Setting MySQL unbuffered mode

<?php
$pdo = new PDO("mysql:host=localhost;dbname=world", 'my_user', 'my_password');
$pdo->setAttribute(PDO::MYSQL_ATTR_USE_BUFFERED_QUERY, false);

$unbufferedResult = $pdo->query("SELECT Name FROM City");
foreach ($unbufferedResult as $row) {
    echo $row['Name'] . PHP_EOL;
}
?>

PDO::MYSQL_ATTR_LOCAL_INFILE (int)

Enable LOAD LOCAL INFILE.

Note, this constant can only be used in the driver_options array when constructing a new database handle.

PDO::MYSQL_ATTR_LOCAL_INFILE_DIRECTORY (string)

Allows restricting LOCAL DATA loading to files located in this designated directory. Available as of PHP 8.1.0.

Note, this constant can only be used in the driver_options array when constructing a new database handle.

PDO::MYSQL_ATTR_INIT_COMMAND (string)

Command to execute when connecting to the MySQL server. Will automatically be re-executed when reconnecting.

Note, this constant can only be used in the driver_options array when constructing a new database handle.

PDO::MYSQL_ATTR_READ_DEFAULT_FILE (int)

Read options from the named option file instead of from my.cnf. This option is not available if mysqlnd is used, because mysqlnd does not read the mysql configuration files.

PDO::MYSQL_ATTR_READ_DEFAULT_GROUP (int)

Read options from the named group from my.cnf or the file specified with MYSQL_READ_DEFAULT_FILE. This option is not available if mysqlnd is used, because mysqlnd does not read the mysql configuration files.

PDO::MYSQL_ATTR_MAX_BUFFER_SIZE (int)

Maximum buffer size. Defaults to 1 MiB. This constant is not supported when compiled against mysqlnd.

PDO::MYSQL_ATTR_DIRECT_QUERY (int)

Perform direct queries, don't use prepared statements.

PDO::MYSQL_ATTR_FOUND_ROWS (int)

Return the number of found (matched) rows, not the number of changed rows.

PDO::MYSQL_ATTR_IGNORE_SPACE (int)

Permit spaces after function names. Makes all functions names reserved words.

PDO::MYSQL_ATTR_COMPRESS (int)

Enable network communication compression.

PDO::MYSQL_ATTR_SSL_CA (int)

The file path to the SSL certificate authority.

PDO::MYSQL_ATTR_SSL_CAPATH (int)

The file path to the directory that contains the trusted SSL CA certificates, which are stored in PEM format.

PDO::MYSQL_ATTR_SSL_CERT (int)

The file path to the SSL certificate.

PDO::MYSQL_ATTR_SSL_CIPHER (int)

A list of one or more permissible ciphers to use for SSL encryption, in a format understood by OpenSSL. For example: DHE-RSA-AES256-SHA:AES128-SHA

PDO::MYSQL_ATTR_SSL_KEY (int)

The file path to the SSL key.

PDO::MYSQL_ATTR_SSL_VERIFY_SERVER_CERT (int)

Provides a way to disable verification of the server SSL certificate. This option is available only with mysqlnd.

Questo esiste dal PHP 7.0.18 and PHP 7.1.4.

PDO::MYSQL_ATTR_MULTI_STATEMENTS (int)

Disables multi query execution in both PDO::prepare() and PDO::query() when set to false.

Note, this constant can only be used in the driver_options array when constructing a new database handle.

Configurazione di Runtime

Il comportamento di queste funzioni è influenzato dalle impostazioni di php.ini.

**PDO_MYSQL Configuration Options**
Nome	Default	Modificabile
pdo_mysql.default_socket	"/tmp/mysql.sock"	`INI_SYSTEM`
pdo_mysql.debug	NULL	`INI_SYSTEM`

Per maggiori dettagli e definizioni sui modi INI_*, vedere Where a configuration setting may be set.

Breve descrizione dei parametri di configurazione.

pdo_mysql.default_socket string: Sets a Unix domain socket. This value can either be set at compile time if a domain socket is found at configure. This ini setting is Unix only.
pdo_mysql.debug bool: Enables debugging for PDO_MYSQL. This setting is only available when PDO_MYSQL is compiled against mysqlnd and in PDO debug mode.

Indice dei contenuti

PDO_MYSQL DSN — Connecting to MySQL databases

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User Contributed Notes 6 notes

down

Desislav Kamenov ¶

6 years ago

There is an important undocumented attribute which disables certificate CN verification available after
5.6.22 (not sure), 7.0.18 (verified) and 7.1.15 (not sure)

PDO::MYSQL_ATTR_SSL_VERIFY_SERVER_CERT

possible values: true, false
default value: true 

Related PHP bugs:
https://bugs.php.net/bug.php?id=71845
https://bugs.php.net/bug.php?id=71003

and github PR: https://github.com/php/php-src/pull/1913

down

davey at php dot net ¶

17 years ago

To use "PDO::MYSQL_ATTR_USE_BUFFERED_QUERY" you should call

PDO::setAttribute(PDO::MYSQL_ATTR_USE_BUFFERED_QUERY, true);



It will not work when passed into PDO::prepare()

down

brian at diamondsea dot com ¶

16 years ago

SQLSTATE[HY000]: General error: 2014 Cannot execute queries while other unbuffered queries are active. ...

After spending hours trying to track down why we were getting this error on a new server, after the same code ran fine on other servers, we found the problem to be an old MySQL _client_ library running on our web server, and a latest-version MySQL _server_ running on the database server's box.

Upgraded the MySQL client on the web server to the current revision and the problem went away.

down

curt at webmasterbond dot com ¶

13 years ago

Today's PHP snapshot now has SSL support for PDO. Follow the directions here ( http://dev.mysql.com/doc/refman/5.0/en/secure-create-certs.html ) to set up MySQL and then use the following connection options:

<?php
$pdo = new PDO(
    'mysql:host=hostname;dbname=ssldb',
    'username',
    'password',
    array(
        PDO::MYSQL_ATTR_SSL_KEY    =>'/path/to/client-key.pem',
        PDO::MYSQL_ATTR_SSL_CERT=>'/path/to/client-cert.pem',
        PDO::MYSQL_ATTR_SSL_CA    =>'/path/to/ca-cert.pem'
    )
);
?>

down

snoyes at gmail dot com ¶

21 days ago

> change it by setting default_authentication_plugin=mysql_native_password in my.cnf

This only works in MySQL 8.0. The default_authentication_plugin variable has been removed from 8.4.

down

-3

rmottey at gmail dot com ¶

16 years ago

I have been getting the error below when performing multiple queries within a single page.

Setting the attribute below did not seem to work for me.

So building on previous example i am initilizing my stmt  variable on every query and a fetch all into an array. Seems to be working for me.

Error:
PDO Error 1.1: Array ( [0] => xxx[1] => yyy[2] => Lost connection to MySQL server during query )

Fix:

(PDO::setAttribute("PDO::MYSQL_ATTR_USE_BUFFERED_QUERY", true);)

<?

try {
        $dbh = new PDO('mysql:host=xxx;port=xxx;dbname=xxx', 'xxx', 'xxx', array( PDO::ATTR_PERSISTENT => false));
 $stmt = $dbh->prepare("CALL getname()");

        // call the stored procedure
        $stmt->execute();
      // fetch all rows into an array.
       $rows = $stmt->fetchAll();
       foreach ($rows as $rs) 
    {
          $id = $rs['id'];
         }
//initilise the statement
unset($stmt);
$stmt = $dbh->prepare("call secondprocedure(?);");
$stmt->bindValue(1, $id);
if ( ! $stmt->execute() )
{
    echo "PDO Error 1.1:\n";
    print_r($stmt->errorInfo());
    exit;
}
unset($stmt);
} catch (PDOException $e) {
        print "Error!: " . $e->getMessage() . "<br/>";
        die();
    }
?>

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