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PDO::__construct (no version information, might be only in CVS) PDO::__construct --
Creates a PDO instance representing a connection to a database
DescriptionPDO 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 <?php
/* 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();
}
?> |
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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:
<?php
/* 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();
}
?> |
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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" |
<?php
/* Connect to an ODBC database using an alias */
$dsn = 'mydb';
$user = '';
$password = '';
try {
$dbh = new PDO($dsn, $user, $password);
}catch (PDOException $e) {
echo 'Connection failed: ' . $e->getMessage();
}
?> |
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PDO::commit
