PDO::__construct
Creates a PDO instance representing a connection to a database
&reftitle.description;
PDOPDO::__constructstringdsnstringusernamestringpasswordarraydriver_options
Creates a PDO instance to represent a connection to the requested
database.
&reftitle.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 invocationdsn contains the full DSN.
URI invocationdsn 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/dsnfileAliasingdsn consists of a name
name that maps to
pdo.dsn.name in &php.ini;
defining the DSN string.
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.
&reftitle.returnvalues;
Returns a PDO object on success.
&reftitle.exceptions;
PDO::construct throws a PDOException if the attempt
to connect to the requested database fails.
&reftitle.examples;
Create a PDO instance via driver invocation
getMessage();
}
?>
]]>
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:
The PHP script can then create a database connection by simply
passing the uri: parameter and pointing to
the file URI:
getMessage();
}
?>
]]>
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"
getMessage();
}
?>
]]>