Mysqli php connection string

mysqli_connect

mysqli() — Открывает новое соединение с MySQL сервером.

mysqli mysqli_connect ( [string host [, string username [, string passwd [, string dbname [, int port [, string socket]]]]]] )

Объектный стиль вызова (constructor):

class mysqli __construct ( [string host [, string username [, string passwd [, string dbname [, int port [, string socket]]]]]] )
>

The mysqli_connect() function attempts to open a connection to the MySQL Server running on host which can be either a host name or an IP address. Passing the NULL value or the string «localhost» to this parameter, the local host is assumed. When possible, pipes will be used instead of the TCP/IP protocol. If successful, the mysqli_connect() will return an object representing the connection to the database, or FALSE on failure.

The username and password parameters specify the username and password under which to connect to the MySQL server. If the password is not provided (the NULL value is passed), the MySQL server will attempt to authenticate the user against those user records which have no password only. This allows one username to be used with different permissions (depending on if a password as provided or not).

The dbname parameter if provided will specify the default database to be used when performing queries.

The port and socket parameters are used in conjunction with the host parameter to further control how to connect to the database server. The port parameter specifies the port number to attempt to connect to the MySQL server on, while the socket parameter specifies the socket or named pipe that should be used.

Замечание: Specifying the socket parameter will not explicitly determine the type of connection to be used when connecting to the MySQL server. How the connection is made to the MySQL database is determined by the host parameter.

Возвращаемые значения

Returns a object which represents the connection to a MySQL Server or FALSE if the connection failed.

Примеры

Пример 1. Object oriented style

$mysqli = new mysqli("localhost", "my_user", "my_password", "world"); /* check connection */ if (mysqli_connect_errno()) < printf("Connect failed: %s\n", mysqli_connect_error()); exit(); >printf("Host information: %s\n", $mysqli->host_info); /* close connection */ $mysqli->close();

Пример 2. Procedural style

$link = mysqli_connect("localhost", "my_user", "my_password", "world"); /* check connection */ if (!$link) < printf("Connect failed: %s\n", mysqli_connect_error()); exit(); >printf("Host information: %s\n", mysqli_get_host_info($link)); /* close connection */ mysqli_close($link);

Результат выполнения данного примера:

Host information: Localhost via UNIX socket

Источник

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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PHP Connect to MySQL

PHP 5 and later can work with a MySQL database using:

• MySQLi extension (the «i» stands for improved)
• PDO (PHP Data Objects)

Earlier versions of PHP used the MySQL extension. However, this extension was deprecated in 2012.

Should I Use MySQLi or PDO?

If you need a short answer, it would be «Whatever you like».

Both MySQLi and PDO have their advantages:

PDO will work on 12 different database systems, whereas MySQLi will only work with MySQL databases.

So, if you have to switch your project to use another database, PDO makes the process easy. You only have to change the connection string and a few queries. With MySQLi, you will need to rewrite the entire code — queries included.

Both are object-oriented, but MySQLi also offers a procedural API.

Both support Prepared Statements. Prepared Statements protect from SQL injection, and are very important for web application security.

MySQL Examples in Both MySQLi and PDO Syntax

In this, and in the following chapters we demonstrate three ways of working with PHP and MySQL:

MySQLi Installation

For Linux and Windows: The MySQLi extension is automatically installed in most cases, when php5 mysql package is installed.

PDO Installation

Open a Connection to MySQL

Before we can access data in the MySQL database, we need to be able to connect to the server:

Example (MySQLi Object-Oriented)

$servername = «localhost»;
$username = «username»;
$password = «password»;

// Create connection
$conn = new mysqli($servername, $username, $password);

// Check connection
if ($conn->connect_error) die(«Connection failed: » . $conn->connect_error);
>
echo «Connected successfully»;
?>

Note on the object-oriented example above:

$connect_error was broken until PHP 5.2.9 and 5.3.0. If you need to ensure compatibility with PHP versions prior to 5.2.9 and 5.3.0, use the following code instead:

// Check connection
if (mysqli_connect_error()) die(«Database connection failed: » . mysqli_connect_error());
>

Example (MySQLi Procedural)

$servername = «localhost»;
$username = «username»;
$password = «password»;

// Create connection
$conn = mysqli_connect($servername, $username, $password);

// Check connection
if (!$conn) die(«Connection failed: » . mysqli_connect_error());
>
echo «Connected successfully»;
?>

Example (PDO)

$servername = «localhost»;
$username = «username»;
$password = «password»;

try $conn = new PDO(«mysql:host=$servername;dbname=myDB», $username, $password);
// set the PDO error mode to exception
$conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
echo «Connected successfully»;
> catch(PDOException $e) echo «Connection failed: » . $e->getMessage();
>
?>

Note: In the PDO example above we have also specified a database (myDB). PDO require a valid database to connect to. If no database is specified, an exception is thrown.

Tip: A great benefit of PDO is that it has an exception class to handle any problems that may occur in our database queries. If an exception is thrown within the try < >block, the script stops executing and flows directly to the first catch() < >block.

Close the Connection

The connection will be closed automatically when the script ends. To close the connection before, use the following:

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