PHP pdo_construct function

PDO->__construct()

(no version information, might be only in CVS)

PDO->__construct() --
Creates a PDO instance representing a connection to a database
Descriptionclass PDO {

PDO __construct ( string dsn [, string username [, string password [, array driver_options]]] )

}

Creates a PDO instance to represent a connection to the requested
database.

Parameters

dsn

The Data Source Name, or DSN, contains the information required to
connect to the database.

In general, a DSN consists of the PDO driver name, followed by a colon,
followed by the PDO driver-specific connection syntax. Further
information is available from the PDO
driver-specific documentation.

The dsn parameter supports three
different methods of specifying the arguments required to create
a database connection:

Driver invocation

dsn contains the full DSN.

URI invocation

dsn consists of uri:
followed by a URI that defines the location of a file containing
the DSN string. The URI can specify a local file or a remote URL.

uri:file:///path/to/dsnfile

Aliasing

dsn consists of a name
name that maps to
pdo.dsn.name in php.ini
defining the DSN string.

Note:
The alias must be defined in php.ini, and not .htaccess or httpd.conf

username

The user name for the DSN string. This parameter is optional for
some PDO drivers.

password

The password for the DSN string. This parameter is optional for
some PDO drivers.

driver_options

A key=>value array of driver-specific connection options.

Return Values

Returns a PDO object on success.

Errors/Exceptions

PDO->__construct() throws a PDOException if the attempt
to connect to the requested database fails.

Examples

Example 1. Create a PDO instance via driver invocation

/* Connect to an ODBC database using driver invocation */
$dsn = 'mysql:dbname=testdb;host=127.0.0.1';
$user = 'dbuser';
$password = 'dbpass';

try {
$dbh = new PDO($dsn, $user, $password);
} catch (PDOException $e) {
echo 'Connection failed: ' . $e->getMessage();
}

Example 2. Create a PDO instance via URI invocation

The following example assumes that the file
/usr/local/dbconnect exists with file permissions
that enable PHP to read the file. The file contains the PDO DSN to
connect to a DB2 database through the PDO_ODBC driver:

odbc:DSN=SAMPLE;UID=john;PWD=mypass

The PHP script can then create a database connection by simply
passing the uri: parameter and pointing to
the file URI:

/* Connect to an ODBC database using driver invocation */
$dsn = 'uri:file:///usr/local/dbconnect';
$user = '';
$password = '';

try {
$dbh = new PDO($dsn, $user, $password);
} catch (PDOException $e) {
echo 'Connection failed: ' . $e->getMessage();
}

Example 3. Create a PDO instance using an alias

The following example assumes that php.ini contains the following
entry to enable a connection to a MySQL database using only the
alias mydb:
[PDO]
pdo.dsn.mydb="mysql:dbname=testdb;host=localhost"