# MySQL Functions (PDO_MYSQL)

## Introduction

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

As of PHP 5.2.1, PDO_MYSQL uses emulated prepares by default. Formerly, PDO_MYSQL defaulted to native prepared statement support present in MySQL 4.1 and higher, and emulated them for older versions of the mysql client libraries.

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 will be supported in a future PHP release. In the meantime, the mysql_xdevapi extension does support it.

Warning

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.

## Installation

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 than 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. As of PHP 5.4, 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.

Changelog
Version | Description
--- | ---
5.4.0 | mysqlnd became the default MySQL library when compiling PDO_MYSQL. Previously, libmysqlclient was the default MySQL library.
5.4.0 | MySQL client libraries 4.1 and below are no longer supported.
5.3.9 | Added SSL support with mysqlnd and OpenSSL.
5.3.7 | Added SSL support with libmysqlclient and OpenSSL.

## Predefined Constants

The constants below are defined by this driver, and will only be available when the extension has been either compiled into PHP or dynamically loaded at runtime. In addition, these driver-specific constants should only be used if you are using this driver. Using driver-specific attributes with another driver may result in unexpected behaviour. PDO::getAttribute() may be used to obtain the `PDO::ATTR_DRIVER_NAME` attribute to check the driver, if your code can run against multiple drivers.

`PDO::MYSQL_ATTR_USE_BUFFERED_QUERY` (int)
  If this attribute is set to `TRUE` on a PDOStatement, the MySQL driver will use the buffered versions of the MySQL API. If you're writing portable code, you should use PDOStatement::fetchAll() instead.

  Example #1 Forcing queries to be buffered in mysql

  `<?php
  if ($db->getAttribute(PDO::ATTR_DRIVER_NAME) == 'mysql') {
  $stmt = $db->prepare('select * from foo',
  array(PDO::MYSQL_ATTR_USE_BUFFERED_QUERY => true));
  } else {
  die("my application only works with mysql; I should use \$stmt->fetchAll() instead");
  }
  ?>`
`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.

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

`PDO::MYSQL_ATTR_INIT_COMMAND` (int)

  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. This is also supported when compiled against mysqlnd as of PHP 5.3.11.

`PDO::MYSQL_ATTR_SSL_CA` (int)

  The file path to the SSL certificate authority.

  This exists as of PHP 5.3.7.

`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.

  This exists as of PHP 5.3.7.

`PDO::MYSQL_ATTR_SSL_CERT` (int)

  The file path to the SSL certificate.

  This exists as of PHP 5.3.7.

`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`

  This exists as of PHP 5.3.7.

`PDO::MYSQL_ATTR_SSL_KEY` (int)

  The file path to the SSL key.

  This exists as of PHP 5.3.7.

`PDO::MYSQL_ATTR_SSL_VERIFY_SERVER_CERT` (int)

  Provides a way to disable verification of the server SSL certificate.

  This exists as of 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.

  This exists as of PHP 5.5.21 and PHP 5.6.5.

## Runtime Configuration

The behaviour of these functions is affected by settings in php.ini.

PDO_MYSQL Configuration Options
Name | Default | Changeable
--- | --- | ---
pdo_mysql.default_socket | "/tmp/mysql.sock" | PHP_INI_SYSTEM
pdo_mysql.debug | NULL | PHP_INI_SYSTEM

For further details and definitions of the PHP_INI_* modes, see the Where a configuration setting may be set.

Here's a short explanation of the configuration directives.

`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.

## Table of Contents

- PDO_MYSQL DSN — Connecting to MySQL databases