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LXII. MySQL Functions

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/.

Requirements

In order to have these functions available, you must compile PHP with MySQL support.

Installation

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.

Runtime Configuration

The behaviour of the MySQL functions is affected by settings in the global configuration file php.ini.

Table 1. MySQL Configuration Options

NameDefaultChangeable
mysql.allow_persistent"On"PHP_INI_SYSTEM
mysql.max_persistent"-1"PHP_INI_SYSTEM
mysql.max_links"-1"PHP_INI_SYSTEM
mysql.default_portNULLPHP_INI_ALL
mysql.default_socketNULLPHP_INI_ALL
mysql.default_hostNULLPHP_INI_ALL
mysql.default_userNULLPHP_INI_ALL
mysql.default_passwordNULLPHP_INI_ALL
For further details and definition of the PHP_INI_* constants see ini_set().

Here is a short explanation of the configuration directives.

mysql.allow_persistent boolean

Wether to allow persistent connections to MySQL.

mysql.max_persistent integer

The maximum number of persistent MySQL connections per process.

mysql.max_links integer

The maximum number of MySQL connections per process, including persistent connections.

mysql.default_port string

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.

mysql.default_socket string

The default socket name to use when connecting to a local database server if no other socket name is specified.

mysql.default_host string

The default server host to use when connecting to the database server if no other host is specified. Doesn't apply in safe mode.

mysql.default_user string

The default user name to use when connecting to the database server if no other name is specified. Doesn't apply in safe mode.

mysql.default_password string

The default password to use when connecting to the database server if no other password is specified. Doesn't apply in safe mode.

Resource types

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.

Predefined constants

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

constantmeaning
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.

Examples

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

<?php
    /* Connecting, selecting database */
    $link = mysql_connect("mysql_host", "mysql_user", "mysql_password")
        or die("Could not connect");
    print "Connected successfully";
    mysql_select_db("my_database") or die("Could not select database");

    /* Performing SQL query */
    $query = "SELECT * FROM my_table";
    $result = mysql_query($query) or die("Query failed");

    /* Printing results in HTML */
    print "<table>\n";
    while ($line = mysql_fetch_array($result, MYSQL_ASSOC)) {
        print "\t<tr>\n";
        foreach ($line as $col_value) {
            print "\t\t<td>$col_value</td>\n";
        }
        print "\t</tr>\n";
    }
    print "</table>\n";

    /* Free resultset */
    mysql_free_result($result);

    /* Closing connection */
    mysql_close($link);
?>

Table of Contents
mysql_affected_rows -- Get number of affected rows in previous MySQL operation
mysql_change_user --  Change logged in user of the active connection
mysql_character_set_name -- Returns the name of the character set
mysql_close -- Close MySQL connection
mysql_connect -- Open a connection to a MySQL Server
mysql_create_db -- Create a MySQL database
mysql_data_seek -- Move internal result pointer
mysql_db_name -- Get result data
mysql_db_query -- Send a MySQL query
mysql_drop_db -- Drop (delete) a MySQL database
mysql_errno --  Returns the numerical value of the error message from previous MySQL operation
mysql_error --  Returns the text of the error message from previous MySQL operation
mysql_escape_string --  Escapes a string for use in a mysql_query.
mysql_fetch_array --  Fetch a result row as an associative array, a numeric array, or both.
mysql_fetch_assoc --  Fetch a result row as an associative array
mysql_fetch_field --  Get column information from a result and return as an object
mysql_fetch_lengths --  Get the length of each output in a result
mysql_fetch_object -- Fetch a result row as an object
mysql_fetch_row -- Get a result row as an enumerated array
mysql_field_flags --  Get the flags associated with the specified field in a result
mysql_field_len --  Returns the length of the specified field
mysql_field_name --  Get the name of the specified field in a result
mysql_field_seek --  Set result pointer to a specified field offset
mysql_field_table --  Get name of the table the specified field is in
mysql_field_type --  Get the type of the specified field in a result
mysql_free_result -- Free result memory
mysql_get_client_info -- Get MySQL client info
mysql_get_host_info -- Get MySQL host info
mysql_get_proto_info -- Get MySQL protocol info
mysql_get_server_info -- Get MySQL server info
mysql_info --  Get information about the most recent query
mysql_insert_id --  Get the id generated from the previous INSERT operation
mysql_list_dbs --  List databases available on a MySQL server
mysql_list_fields -- List MySQL result fields
mysql_list_processes -- List MySQL processes
mysql_list_tables -- List tables in a MySQL database
mysql_num_fields -- Get number of fields in result
mysql_num_rows -- Get number of rows in result
mysql_pconnect --  Open a persistent connection to a MySQL server
mysql_ping -- Ping a server connection or reconnect if there is no connection
mysql_query -- Send a MySQL query
mysql_real_escape_string --  Escapes special characters in a string for use in a SQL statement, taking into account the current charset of the connection.
mysql_result -- Get result data
mysql_select_db -- Select a MySQL database
mysql_stat -- Get current system status
mysql_tablename -- Get table name of field
mysql_thread_id -- Return the current thread id
mysql_unbuffered_query --  Send an SQL query to MySQL, without fetching and buffering the result rows
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