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://www.mysql.com/documentation/.
In order to have these functions available, you must compile PHP with MySQL support.
By using the --with-mysql configuration option you enable PHP to access MySQL databases. If you use this option without specifying the path to MySQL, PHP will use the built-in MySQL client libraries. With PHP4 MySQL support is always enabled; if you don't specify the configure option, the bundled libraries are used. Users who run other applications that use MySQL (for example, running PHP 3 and PHP 4 as concurrent apache modules, or auth-mysql) should always specify the path to MySQL: --with-mysql=/path/to/mysql. This will force PHP to use the client libraries installed by MySQL, avoiding any conflicts.
The behaviour of the MySQL functions is affected by settings in the global configuration file php.ini.
Table 1. MySQL Configuration Options
Here is a short explanation of the configuration directives.
Wether 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.
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 safe mode.
The default user name to use when connecting to the database server if no other name is specified. Doesn't apply in safe mode.
The default password to use when connecting to the database server if no other password is specified. Doesn't apply in safe mode.
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 helds the result of a query.
The function mysql_fetch_array() uses a constant for the different types of result arrays. The following constants are defined:
Table 2. 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.|
|MYSQL_STORE_RESULT||Specifies that the MySQL result should be buffered.|
|MYSQL_USE_RESULT||Specifies that the MySQL result should not be buffered.|
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