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XCIII. MySQL Functions
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.
MySQL is not enabled by default, nor is the MySQL library
bundled with PHP. Read this
FAQ for details on why. Use the
--with-mysql[=DIR] configure option
to include MySQL support.
You can download headers and libraries from
MySQL.
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.
| Warning |
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 | Name | Default | Changeable | Changelog |
|---|
| mysql.allow_persistent | "1" | PHP_INI_SYSTEM | | | mysql.max_persistent | "-1" | PHP_INI_SYSTEM | | | mysql.max_links | "-1" | PHP_INI_SYSTEM | | | mysql.trace_mode | "0" | PHP_INI_ALL | Available since PHP 4.3.0. | | mysql.default_port | NULL | PHP_INI_ALL | | | mysql.default_socket | NULL | PHP_INI_ALL | Available since PHP 4.0.1. | | mysql.default_host | NULL | PHP_INI_ALL | | | mysql.default_user | NULL | PHP_INI_ALL | | | mysql.default_password | NULL | PHP_INI_ALL | | | mysql.connect_timeout | "60" | PHP_INI_ALL | PHP_INI_SYSTEM in PHP <= 4.3.2. Available since PHP 4.3.0. |
For further details and definitions of the
PHP_INI_* constants, see the Appendix G.
Here's a short explanation of
the configuration directives.
- mysql.allow_persistent
boolean
Whether 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.trace_mode
boolean
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)
- 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
SQL 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
SQL 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
SQL safe mode.
- mysql.connect_timeout
integer
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.
Since PHP 4.3.0 it is possible to specify additional client flags for the
mysql_connect() and mysql_pconnect()
functions. The following constants are defined:
Table 2. MySQL client constants | Constant | Description |
|---|
| 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 | Constant | Description |
|---|
| 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.
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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 <?php
// Connecting, selecting database
$link = mysql_connect('mysql_host', 'mysql_user', 'mysql_password')
or die('Could not connect: ' . mysql_error());
echo '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: ' . mysql_error());
// Printing results in HTML
echo "<table>\n";
while ($line = mysql_fetch_array($result, MYSQL_ASSOC)) {
echo "\t<tr>\n";
foreach ($line as $col_value) {
echo "\t\t<td>$col_value</td>\n";
}
echo "\t</tr>\n";
}
echo "</table>\n";
// Free resultset
mysql_free_result($result);
// Closing connection
mysql_close($link);
?> |
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muscat_setup
