# MySQL Functions (PDO_MYSQL)

&reftitle.intro;

PDO_MYSQL is a driver that implements the PHP Data Objects (PDO) interface to enable access from PHP to MySQL 3.x, 4.x and 5.x databases.

PDO_MYSQL will take advantage of native prepared statement support present in MySQL 4.1 and higher. If you're using an older version of the mysql client libraries, PDO will emulate them for you.

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.

&reference.pdo-mysql.configure; &reference.pdo-mysql.constants; &reference.pdo-mysql.ini;

PDO_MYSQL DSN

Connecting to MySQL databases

&reftitle.description;

The PDO_MYSQL Data Source Name (DSN) is composed of the following elements:

DSN prefix

- The DSN prefix is `mysql:`.

`host`

- The hostname on which the database server resides.

`port`

- The port number where the database server is listening.

`dbname`

- The name of the database.

`unix_socket`

- The MySQL Unix socket (shouldn't be used with `host` or `port`).

`charset`

- The character set. See the character set concepts documentation for more information.

  Prior to PHP 5.3.6, this element was silently ignored. The same behaviour can be partly replicated with the `PDO::MYSQL_ATTR_INIT_COMMAND` driver option, as the following example shows.

  The method in the below example can only be used with character sets that share the same lower 7 bit representation as ASCII, such as ISO-8859-1 and UTF-8. Users using character sets that have different representations (such as UTF-16 or Big5) must use the `charset` option provided in PHP 5.3.6 and later versions.

  #### Setting the connection character set to UTF-8 prior to PHP 5.3.6

      <?php
      $dsn = 'mysql:host=localhost;dbname=testdb';
      $username = 'username';
      $password = 'password';
      $options = array(
          PDO::MYSQL_ATTR_INIT_COMMAND => 'SET NAMES utf8',
      );

      $dbh = new PDO($dsn, $username, $password, $options);
      ?>

&reftitle.changelog;

&Version; | &Description;
5.3.6 | Prior to version 5.3.6, `charset` was ignored.

&reftitle.examples;

#### PDO_MYSQL DSN examples

The following example shows a PDO_MYSQL DSN for connecting to MySQL databases:

    mysql:host=localhost;dbname=testdb

More complete examples:

    mysql:host=localhost;port=3307;dbname=testdb
    mysql:unix_socket=/tmp/mysql.sock;dbname=testdb

&reftitle.notes;

#### Unix only:

When the host name is set to `"localhost"`, then the connection to the server is made thru a domain socket. If PDO_MYSQL is compiled against libmysqlclient then the location of the socket file is at libmysqlclient's compiled in location. If PDO_MYSQL is compiled against mysqlnd a default socket can be set thru the pdo_mysql.default_socket setting.