Php ext pdo mysql

Connecting to MySQL

Summary: in this tutorial, you’ll learn step by step how to connect to a MySQL database from PHP using PDO.

Prerequisites

Before connecting to a MySQL database server, you need to have:

• A MySQL database server, a database, and an account that has access to the database.
• PDO MySQL driver enabled in the php.ini file

1) Setting MySQL database parameters

Suppose you have a local MySQL database server that has the following information:

• The host is localhost .
• The bookdb database on the local database server.
• The account with the user root and password ‘S@cr@t1!’ that can access the bookdb database.

In PHP, you can create a config.php file and place the database parameters:

 $host = 'localhost'; $db = 'bookdb'; $user = 'root'; $password = 'S@cr@t1!';Code language: HTML, XML (xml)

To use the database parameters, you can include the config.php file using the require construct:

 require 'config.php';Code language: HTML, XML (xml)

2) Enable PDO_MySQL Driver

PDO_MYSQL is a driver that implements the PDO interface. PDO uses the PDO_MYSQL driver to connect to a MySQL database.

To check if the PDO_MYSQL driver is enabled, you open the php.ini file. The php.ini file is often located under the php directory. For example, you can find the php.ini file under the C:\xampp\php directory if you use XAMPP on Windows.

The following shows the extension line in the php.ini file:

;extension=php_pdo_mysql.dll

To enable the extension, you need to uncomment it by removing the semicolon ( ; ) from the beginning of the line like this:

extension=php_pdo_mysql.dll

After that, you need to restart the web server for the change to take effect.

MySQL data source name

PDO uses a data source name (DSN) that contains the following information:

• The database server host
• The database name
• The user
• The password
• and other parameters such as character sets, etc.

PDO uses this information to make a connection to the database server. To connect to the MySQL database server, you use the following data source name format:

"mysql:host=host_name;dbname=db_name;charset=UTF8"Code language: JSON / JSON with Comments (json)

$dsn = "mysql:host=localhost;dbname=bookdb;charset=UTF8";Code language: PHP (php)

Note that the charset UTF-8 sets the character set of the database connection to UTF-8.

Connecting to MySQL

The following index.php script illustrates how to connect to the bookdb database on the MySQL database server with the root account:

 require 'config.php'; $dsn = "mysql:host=$host;dbname=$db;charset=UTF8"; try < $pdo = new PDO($dsn, $user, $password); if ($pdo) < echo "Connected to the $db database successfully!"; > > catch (PDOException $e) < echo $e->getMessage(); >Code language: HTML, XML (xml)

• First, create a new PDO object with the data source name, user, and password. The PDO object is an instance of the PDO class.
• Second, show the success message if the connection is established successfully or an error message if an error occurs.

If you have everything set up correctly, you will see the following message:

Connected to the bookdb database successfully!Code language: plaintext (plaintext)

Error handling strategies

PDO supports three different error handling strategies:

• PDO::ERROR_SILENT – PDO sets an error code for inspecting using the PDO::errorCode() and PDO::errorInfo() methods. The PDO::ERROR_SILENT is the default mode.
• PDO::ERRMODE_WARNING – Besides setting the error code, PDO will issue an E_WARNING message.
• PDO::ERRMODE_EXCEPTION – Besides setting the error code, PDO will raise a PDOException .

To set the error handling strategy, you can pass an associative array to the PDO constructor like this:

$pdo = new PDO($dsn, $user, $password, [PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION]);Code language: PHP (php)

Or you can use the setAttribute() method of the PDO instance:

$pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);Code language: PHP (php)

Troubleshooting

There are some common issues when you connect to a MySQL database:

If the MySQL driver is not enabled in the php.ini file, you will get the error message:

could not find driverCode language: plaintext (plaintext)

If you provide an incorrect password, you get the following error message:

SQLSTATE[HY000] [1045] Access denied for user 'root'@'localhost' (using password: YES)Code language: plaintext (plaintext)

If you provide an invalid database name or the database does not exist, you get the following error message:

SQLSTATE[HY000] [1049] Unknown database 'bookdb'Code language: plaintext (plaintext)

If you provide an invalid database hostname, the following error message will display:

SQLSTATE[HY000] [2002] php_network_getaddresses: getaddrinfo failed: No such host is known.Code language: plaintext (plaintext)

Summary

• Enable the PDO_MYSQL driver in the php.ini file for connecting to a MySQL database from PHP PDO.
• Create an instance of the PDO class to make a connection to a MySQL database.
• Use the PDO constructor or the setAttribute() method to set an error handling strategy.

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MySQL Functions (PDO_MYSQL)

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.

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.

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.

Note:

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).

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 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.

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 ( 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

$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 ;
>
?>

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 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.

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.

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.

Enables debugging for PDO_MYSQL. This setting is only available when PDO_MYSQL is compiled against mysqlnd and in PDO debug mode.

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