PDO does not account for database specific syntax. It can allow for the process of switching databases and platforms. PDO can simply switch the connection string in many instances.

PDO supports the following database:

PDO_FIREBIRD ( Firebird/Interbase 6 )
PDO_DBLIB ( FreeTDS / Microsoft SQL Server / Sybase )
PDO_IBM ( IBM DB2 )
PDO_INFORMIX ( IBM Informix Dynamic Server )
PDO_MYSQL ( MySQL 3.x/4.x/5.x )
PDO_OCI ( Oracle Call Interface )
PDO_ODBC ( ODBC v3 (IBM DB2, unixODBC and win32 ODBC) )
PDO_PGSQL ( PostgreSQL )
PDO_SQLITE ( SQLite 3 and SQLite 2 )
PDO_4D ( 4D )

Database connection string for some databases:

$servername = "localhost";
$username = "username";
$password = "password";
try {
 $DBH = new PDO("mssql:host=$host;dbname=$dbname, $user, $pass");
 $DBH = new PDO("sybase:host=$host;dbname=$dbname, $user, $pass");
 # MySQL with PDO_MYSQL
 $DBH = new PDO("mysql:host=$host;dbname=$dbname", $user, $pass);
 # SQLite Database
 $DBH = new PDO("sqlite:my/database/path/database.db");
// set the PDO error mode to exception
$DBH->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
 echo "Connected successfully";
 }
catch(PDOException $e)
{
echo "Connection failed: " . $e->getMessage();
 }
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