CDbConnection

CDbConnection represents a connection to a database.

CDbConnection works together with {@link CDbCommand}, {@link CDbDataReader} and {@link CDbTransaction} to provide data access to various DBMS in a common set of APIs. They are a thin wrapper of the {@link http://www.php.net/manual/en/ref.pdo.php PDO} PHP extension. To establish a connection, set {@link setActive active} to true after specifying {@link connectionString}, {@link username} and {@link password}. The following example shows how to create a CDbConnection instance and establish the actual connection:

$connection=new CDbConnection($dsn,$username,$password);
$connection->active=true;

After the DB connection is established, one can execute an SQL statement like the following:

$command=$connection->createCommand($sqlStatement);
$command->execute();   // a non-query SQL statement execution
// or execute an SQL query and fetch the result set
$reader=$command->query();

// each $row is an array representing a row of data
foreach($reader as $row) ...

One can do prepared SQL execution and bind parameters to the prepared SQL:

$command=$connection->createCommand($sqlStatement);
$command->bindParam($name1,$value1);
$command->bindParam($name2,$value2);
$command->execute();

To use transaction, do like the following:

$transaction=$connection->beginTransaction();
try
{
   $connection->createCommand($sql1)->execute();
   $connection->createCommand($sql2)->execute();
   //.... other SQL executions
   $transaction->commit();
}
catch(Exception $e)
{
   $transaction->rollback();
}

CDbConnection also provides a set of methods to support setting and querying of certain DBMS attributes, such as {@link getNullConversion nullConversion}. Since CDbConnection implements the interface IApplicationComponent, it can be used as an application component and be configured in application configuration, like the following,

array(
    'components'=>array(
        'db'=>array(
            'class'=>'CDbConnection',
            'connectionString'=>'sqlite:path/to/dbfile',
        ),
    ),
)