# MySQL PDO Driver (PDO_MYSQL)

## 简介

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.

警告

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.

> 注意:

> 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).

## 安装

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::ATTR_SSL_*`, 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.

## 预定义常量

下列常量由此驱动定义，且仅在扩展编译入 PHP 或在运行时动态载入时可用。另外，使用此驱动时，仅会使用这些驱动特定的常量。使用其他驱动的驱动特定的常量可能会导致不可预见的情况。如果代码可运行于多个驱动，PDO::getAttribute() 可被用于获取 `PDO_ATTR_DRIVER_NAME` 属性以检查驱动。

`PDO::MYSQL_ATTR_USE_BUFFERED_QUERY` (int)
  别名 `Pdo\Mysql::ATTR_USE_BUFFERED_QUERY`
`PDO::MYSQL_ATTR_LOCAL_INFILE` (int)
  别名 `Pdo\Mysql::ATTR_LOCAL_INFILE`
`PDO::MYSQL_ATTR_LOCAL_INFILE_DIRECTORY` (int)
  别名 `Pdo\Mysql::ATTR_LOCAL_INFILE_DIRECTORY`. Available as of PHP 8.1.0.
`PDO::MYSQL_ATTR_INIT_COMMAND` (int)
  别名 `Pdo\Mysql::ATTR_INIT_COMMAND`
`PDO::MYSQL_ATTR_READ_DEFAULT_FILE` (int)
  别名 `Pdo\Mysql::ATTR_READ_DEFAULT_FILE`
`PDO::MYSQL_ATTR_READ_DEFAULT_GROUP` (int)
  别名 `Pdo\Mysql::ATTR_READ_DEFAULT_GROUP`
`PDO::MYSQL_ATTR_MAX_BUFFER_SIZE` (int)
  别名 `Pdo\Mysql::ATTR_MAX_BUFFER_SIZE`
`PDO::MYSQL_ATTR_DIRECT_QUERY` (int)
  别名 `PDO::ATTR_EMULATE_PREPARES`
`PDO::MYSQL_ATTR_FOUND_ROWS` (int)
  别名 `Pdo\Mysql::ATTR_FOUND_ROWS`
`PDO::MYSQL_ATTR_IGNORE_SPACE` (int)
  别名 `Pdo\Mysql::ATTR_IGNORE_SPACE`
`PDO::MYSQL_ATTR_COMPRESS` (int)
  别名 `Pdo\Mysql::ATTR_COMPRESS`
`PDO::MYSQL_ATTR_SERVER_PUBLIC_KEY` (int)
  别名 `Pdo\Mysql::ATTR_SERVER_PUBLIC_KEY`
`PDO::MYSQL_ATTR_SSL_CA` (int)
  别名 `Pdo\Mysql::ATTR_SSL_CA`
`PDO::MYSQL_ATTR_SSL_CAPATH` (int)
  别名 `Pdo\Mysql::ATTR_SSL_CAPATH`
`PDO::MYSQL_ATTR_SSL_CERT` (int)
  别名 `Pdo\Mysql::ATTR_SSL_CERT`
`PDO::MYSQL_ATTR_SSL_CIPHER` (int)
  别名 `Pdo\Mysql::ATTR_SSL_CIPHER`
`PDO::MYSQL_ATTR_SSL_KEY` (int)
  别名 `Pdo\Mysql::ATTR_SSL_KEY`
`PDO::MYSQL_ATTR_SSL_VERIFY_SERVER_CERT` (int)
  别名 `Pdo\Mysql::ATTR_SSL_VERIFY_SERVER_CERT` Available as of PHP 7.0.18 and PHP 7.1.4.
`PDO::MYSQL_ATTR_MULTI_STATEMENTS` (int)
  别名 `Pdo\Mysql::ATTR_MULTI_STATEMENTS`

## 运行时配置

这些函数的行为受 php.ini 中的设置影响。

PDO_MYSQL Configuration Options
名字 | 默认 | 可修改范围
--- | --- | ---
pdo_mysql.default_socket | "/tmp/mysql.sock" | `INI_SYSTEM`
pdo_mysql.debug | NULL | `INI_SYSTEM`

有关 INI_* 样式的更多详情与定义，见 配置可被设定范围。

这是配置指令的简短说明。

`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.

## 目录

- PDO_MYSQL DSN — Connecting to MySQL databases

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