Php mysqli with port
The behaviour of these functions is affected by settings in php.ini .
| Name | Default | Changeable | Changelog |
|---|---|---|---|
| mysqli.allow_local_infile | «0» | PHP_INI_SYSTEM | Before PHP 7.2.16 and 7.3.3 the default was «1». |
| mysqli.local_infile_directory | PHP_INI_SYSTEM | Available as of PHP 8.1.0. | |
| mysqli.allow_persistent | «1» | PHP_INI_SYSTEM | |
| mysqli.max_persistent | «-1» | PHP_INI_SYSTEM | |
| mysqli.max_links | «-1» | PHP_INI_SYSTEM | |
| mysqli.default_port | «3306» | PHP_INI_ALL | |
| mysqli.default_socket | NULL | PHP_INI_ALL | |
| mysqli.default_host | NULL | PHP_INI_ALL | |
| mysqli.default_user | NULL | PHP_INI_ALL | |
| mysqli.default_pw | NULL | PHP_INI_ALL | |
| mysqli.reconnect | «0» | PHP_INI_SYSTEM | Removed as of PHP 8.2.0 |
| mysqli.rollback_on_cached_plink | «0» | PHP_INI_SYSTEM |
For further details and definitions of the preceding PHP_INI_* constants, see the chapter on configuration changes.
Here’s a short explanation of the configuration directives.
Allow accessing, from PHP’s perspective, local files with LOAD DATA statements
Allows restricting LOCAL DATA loading to files located in this designated directory.
Enable the ability to create persistent connections using mysqli_connect() .
Maximum of persistent connections that can be made. Set to 0 for unlimited.
The maximum number of MySQL connections per process.
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.
The default user name to use when connecting to the database server if no other name is specified.
The default password to use when connecting to the database server if no other password is specified.
Automatically reconnect if the connection was lost.
Note: This php.ini setting had been ignored by the mysqlnd driver, and was removed as of PHP 8.2.0.
If this option is enabled, closing a persistent connection will rollback any pending transactions of this connection before it is put back into the persistent connection pool. Otherwise, pending transactions will be rolled back only when the connection is reused, or when it is actually closed.
Users cannot set MYSQL_OPT_READ_TIMEOUT through an API call or runtime configuration setting. Note that if it were possible there would be differences between how libmysqlclient and streams would interpret the value of MYSQL_OPT_READ_TIMEOUT .
Php mysqli with port
The MySQL server supports the use of different transport layers for connections. Connections use TCP/IP, Unix domain sockets or Windows named pipes.
The hostname localhost has a special meaning. It is bound to the use of Unix domain sockets. To open a TCP/IP connection to the localhost, 127.0.0.1 must be used instead of the hostname localhost .
Example #1 Special meaning of localhost
$mysqli = new mysqli ( «localhost» , «user» , «password» , «database» );
echo $mysqli -> host_info . «\n» ;
$mysqli = new mysqli ( «127.0.0.1» , «user» , «password» , «database» , 3306 );
echo $mysqli -> host_info . «\n» ;
The above example will output:
Localhost via UNIX socket 127.0.0.1 via TCP/IP
Connection parameter defaults
Depending on the connection function used, assorted parameters can be omitted. If a parameter is not provided, then the extension attempts to use the default values that are set in the PHP configuration file.
Example #2 Setting defaults
mysqli.default_host=192.168.2.27 mysqli.default_user=root mysqli.default_pw="" mysqli.default_port=3306 mysqli.default_socket=/tmp/mysql.sock
The resulting parameter values are then passed to the client library that is used by the extension. If the client library detects empty or unset parameters, then it may default to the library built-in values.
Built-in connection library defaults
If the host value is unset or empty, then the client library will default to a Unix socket connection on localhost . If socket is unset or empty, and a Unix socket connection is requested, then a connection to the default socket on /tmp/mysql.sock is attempted.
On Windows systems, the host name . is interpreted by the client library as an attempt to open a Windows named pipe based connection. In this case the socket parameter is interpreted as the pipe name. If not given or empty, then the socket (pipe name) defaults to \\.\pipe\MySQL .
If neither a Unix domain socket based not a Windows named pipe based connection is to be established and the port parameter value is unset, the library will default to port 3306 .
The mysqlnd library and the MySQL Client Library (libmysqlclient) implement the same logic for determining defaults.
Connection options are available to, for example, set init commands which are executed upon connect, or for requesting use of a certain charset. Connection options must be set before a network connection is established.
For setting a connection option, the connect operation has to be performed in three steps: creating a connection handle with mysqli_init() or mysqli::__construct() , setting the requested options using mysqli::options() , and establishing the network connection with mysqli::real_connect() .
The mysqli extension supports persistent database connections, which are a special kind of pooled connections. By default, every database connection opened by a script is either explicitly closed by the user during runtime or released automatically at the end of the script. A persistent connection is not. Instead it is put into a pool for later reuse, if a connection to the same server using the same username, password, socket, port and default database is opened. Reuse saves connection overhead.
Every PHP process is using its own mysqli connection pool. Depending on the web server deployment model, a PHP process may serve one or multiple requests. Therefore, a pooled connection may be used by one or more scripts subsequently.
If an unused persistent connection for a given combination of host, username, password, socket, port and default database cannot be found in the connection pool, then mysqli opens a new connection. The use of persistent connections can be enabled and disabled using the PHP directive mysqli.allow_persistent. The total number of connections opened by a script can be limited with mysqli.max_links. The maximum number of persistent connections per PHP process can be restricted with mysqli.max_persistent. Please note that the web server may spawn many PHP processes.
A common complain about persistent connections is that their state is not reset before reuse. For example, open and unfinished transactions are not automatically rolled back. But also, authorization changes which happened in the time between putting the connection into the pool and reusing it are not reflected. This may be seen as an unwanted side-effect. On the contrary, the name persistent may be understood as a promise that the state is persisted.
The mysqli extension supports both interpretations of a persistent connection: state persisted, and state reset before reuse. The default is reset. Before a persistent connection is reused, the mysqli extension implicitly calls mysqli::change_user() to reset the state. The persistent connection appears to the user as if it was just opened. No artifacts from previous usages are visible.
The mysqli::change_user() call is an expensive operation. For best performance, users may want to recompile the extension with the compile flag MYSQLI_NO_CHANGE_USER_ON_PCONNECT being set.
It is left to the user to choose between safe behavior and best performance. Both are valid optimization goals. For ease of use, the safe behavior has been made the default at the expense of maximum performance.
PHP mysqli connect() Function
The connect() / mysqli_connect() function opens a new connection to the MySQL server.
Syntax
Object oriented style:
Procedural style:
Parameter Values
| Parameter | Description |
|---|---|
| host | Optional. Specifies a host name or an IP address |
| username | Optional. Specifies the MySQL username |
| password | Optional. Specifies the MySQL password |
| dbname | Optional. Specifies the default database to be used |
| port | Optional. Specifies the port number to attempt to connect to the MySQL server |
| socket | Optional. Specifies the socket or named pipe to be used |
Technical Details
Example — Procedural style
Open a new connection to the MySQL server:
// Check connection
if (mysqli_connect_errno()) echo «Failed to connect to MySQL: » . mysqli_connect_error();
exit();
>
?>
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