Requirements
In order to have these functions available, you must compile PHP with
MySQL support.
Installation
By using the --with-mysql[=DIR]
configuration option you enable PHP to access MySQL
databases.
In PHP 4, the option --with-mysql is
enabled by default. To disable this default behavior, you may use the
--without-mysql configure option.
Also in PHP 4, if you enable MySQL without specifying the path to the
MySQL install DIR, PHP will use the bundled MySQL client
libraries. In Windows, there is no DLL, it's simply built into PHP 4.
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.
In PHP 5, MySQL is no longer enabled by default, nor is the MySQL library
bundled with PHP. Read this
FAQ for details on why.
This MySQL extension doesn't support full functionality of MySQL versions greater than
4.1.0. For that, use MySQLi.
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.
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.
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Note:
If you need charsets other than latin (default), you
have to install external (not bundled) libmysql with compiled charset
support.
Runtime Configuration
The behaviour of these functions is affected by settings in php.ini.
Table 1. MySQL Configuration Options
Name | Default | Changeable |
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mysql.allow_persistent | "On" | PHP_INI_SYSTEM |
mysql.max_persistent | "-1" | PHP_INI_SYSTEM |
mysql.max_links | "-1" | PHP_INI_SYSTEM |
mysql.default_port | NULL | PHP_INI_ALL |
mysql.default_socket | NULL | PHP_INI_ALL |
mysql.default_host | NULL | PHP_INI_ALL |
mysql.default_user | NULL | PHP_INI_ALL |
mysql.default_password | NULL | PHP_INI_ALL |
mysql.connect_timeout | "0" | PHP_INI_SYSTEM |
For further details and definition of the PHP_INI_* constants see
ini_set().
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.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.
- mysql.connect_timeout
integer
Connect timeout in seconds. On Linux this timeout is also used for
waiting for the first answer from the server.
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 holds the result of a query.
Predefined Constants
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. |
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.
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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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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 : " . 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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