These functions allow you to access MySQL database servers. More information about MySQL can be found at http://www.mysql.com/.
Documentation for MySQL can be found at http://dev.mysql.com/doc/.
In order to have these functions available, you must compile PHP with MySQL support.
For compiling, simply use the --with-mysql[=DIR] configuration option where the optional [DIR] points to the MySQL installation directory.
Although this MySQL extension is compatible with MySQL 4.1.0 and greater, it doesn't support the extra functionality that these versions provide. For that, use the MySQLi extension.
If you would like to install the mysql extension along with the mysqli extension you have to use the same client library to avoid any conflicts.
The option --with-mysql is enabled by default. This default behavior may be disabled with the --without-mysql configure option. If MySQL is enabled without specifying the path to the MySQL install DIR, PHP will use the bundled MySQL client libraries.
Users who run other applications that use MySQL (for example, auth-mysql) should not use the bundled library, but rather specify the path to MySQL's install directory, like so: --with-mysql=/path/to/mysql. This will force PHP to use the client libraries installed by MySQL, thus avoiding any conflicts.
The PHP MySQL extension is compiled into PHP.
MySQL is no longer enabled by default, so the php_mysql.dll DLL must be enabled inside of php.ini. Also, PHP needs access to the MySQL client library. A file named libmysql.dll is included in the Windows PHP distribution and in order for PHP to talk to MySQL this file needs to be available to the Windows systems PATH. See the FAQ titled "How do I add my PHP directory to the PATH on Windows" for information on how to do this. Although copying libmysql.dll to the Windows system directory also works (because the system directory is by default in the system's PATH), it's not recommended.
As with enabling any PHP extension (such as php_mysql.dll), the PHP directive extension_dir should be set to the directory where the PHP extensions are located. See also the Manual Windows Installation Instructions. An example extension_dir value for PHP 5 is c:\php\ext
Note: If when starting the web server an error similar to the following occurs: "Unable to load dynamic library './php_mysql.dll'", this is because php_mysql.dll and/or libmysql.dll cannot be found by the system.
Crashes and startup problems of PHP may be encountered when loading this extension in conjunction with the recode extension. See the recode extension for more information.
Note: If you need charsets other than latin (default), you have to install external (not bundled) libmysql with compiled charset support.
The behaviour of these functions is affected by settings in php.ini.
Table 1. MySQL Configuration Options
|mysql.trace_mode||"0"||PHP_INI_ALL||Available since PHP 4.3.0.|
|mysql.default_socket||NULL||PHP_INI_ALL||Available since PHP 4.0.1.|
|mysql.connect_timeout||"60"||PHP_INI_ALL||PHP_INI_SYSTEM in PHP <= 4.3.2. Available since PHP 4.3.0.|
Here's a short explanation of the configuration directives.
Whether to allow persistent connections to MySQL.
The maximum number of persistent MySQL connections per process.
The maximum number of MySQL connections per process, including persistent connections.
Trace mode. When mysql.trace_mode is enabled, warnings for table/index scans, non free result sets, and SQL-Errors will be displayed. (Introduced in PHP 4.3.0)
The default TCP port number to use when connecting to the database server if no other port is specified. If no default is specified, the port will be obtained from the MYSQL_TCP_PORT environment variable, the mysql-tcp entry in /etc/services or the compile-time MYSQL_PORT constant, in that order. Win32 will only use the MYSQL_PORT constant.
The default socket name to use when connecting to a local database server if no other socket name is specified.
The default server host to use when connecting to the database server if no other host is specified. Doesn't apply in SQL safe mode.
The default user name to use when connecting to the database server if no other name is specified. Doesn't apply in SQL safe mode.
The default password to use when connecting to the database server if no other password is specified. Doesn't apply in SQL safe mode.
Connect timeout in seconds. On Linux this timeout is also used for waiting for the first answer from the server.
There are two resource types used in the MySQL module. The first one is the link identifier for a database connection, the second a resource which holds the result of a query.
The constants below are defined by this extension, and will only be available when the extension has either been compiled into PHP or dynamically loaded at runtime.
Table 2. MySQL client constants
|MYSQL_CLIENT_COMPRESS||Use compression protocol|
|MYSQL_CLIENT_IGNORE_SPACE||Allow space after function names|
|MYSQL_CLIENT_INTERACTIVE||Allow interactive_timeout seconds (instead of wait_timeout) of inactivity before closing the connection.|
|MYSQL_CLIENT_SSL||Use SSL encryption. This flag is only available with version 4.x of the MySQL client library or newer. Version 3.23.x is bundled both with PHP 4 and Windows binaries of PHP 5.|
The function mysql_fetch_array() uses a constant for the different types of result arrays. The following constants are defined:
Table 3. MySQL fetch constants
|MYSQL_ASSOC||Columns are returned into the array having the fieldname as the array index.|
|MYSQL_BOTH||Columns are returned into the array having both a numerical index and the fieldname as the array index.|
|MYSQL_NUM||Columns are returned into the array having a numerical index to the fields. This index starts with 0, the first field in the result.|
Note: Most MySQL functions accept link_identifier as the last optional parameter. If it is not provided, last opened connection is used. If it doesn't exist, connection is tried to establish with default parameters defined in php.ini. If it is not successful, functions return FALSE.
This simple example shows how to connect, execute a query, print resulting rows and disconnect from a MySQL database.
Example 1. MySQL extension overview example