CDbHttpSession

protected function createSessionTable($db,$tableName)
{
    switch($db->getDriverName())
    {
        case 'mysql':
            $blob='LONGBLOB';
            break;
        case 'pgsql':
            $blob='BYTEA';
            break;
        case 'sqlsrv':
        case 'mssql':
        case 'dblib':
            $blob='VARBINARY(MAX)';
            break;
        default:
            $blob='BLOB';
            break;
    }
    $db->createCommand()->createTable($tableName,array(
        'id'=>'CHAR(32) PRIMARY KEY',
        'expire'=>'integer',
        'data'=>$blob,
    ));
}

public function destroySession($id)
{
    $this->getDbConnection()->createCommand()
        ->delete($this->sessionTableName,'id=:id',array(':id'=>$id));
    return true;
}

public function gcSession($maxLifetime)
{
    $this->getDbConnection()->createCommand()
        ->delete($this->sessionTableName,'expire<:expire',array(':expire'=>time()));
    return true;
}

protected function getDbConnection()
{
    if($this->_db!==null)
        return $this->_db;
    elseif(($id=$this->connectionID)!==null)
    {
        if(($this->_db=Yii::app()->getComponent($id)) instanceof CDbConnection)
            return $this->_db;
        else
            throw new CException(Yii::t('yii','CDbHttpSession.connectionID "{id}" is invalid. Please make sure it refers to the ID of a CDbConnection application component.',
                array('{id}'=>$id)));
    }
    else
    {
        $dbFile=Yii::app()->getRuntimePath().DIRECTORY_SEPARATOR.'session-'.Yii::getVersion().'.db';
        return $this->_db=new CDbConnection('sqlite:'.$dbFile);
    }
}

public function getUseCustomStorage()
{
    return true;
}

public function openSession($savePath,$sessionName)
{
    if($this->autoCreateSessionTable)
    {
        $db=$this->getDbConnection();
        $db->setActive(true);
        try
        {
            $db->createCommand()->delete($this->sessionTableName,'expire<:expire',array(':expire'=>time()));
        }
        catch(Exception $e)
        {
            $this->createSessionTable($db,$this->sessionTableName);
        }
    }
    return true;
}

public function readSession($id)
{
    $db=$this->getDbConnection();
    if($db->getDriverName()=='sqlsrv' || $db->getDriverName()=='mssql' || $db->getDriverName()=='dblib')
        $select='CONVERT(VARCHAR(MAX), data)';
    else
        $select='data';
    $data=$db->createCommand()
        ->select($select)
        ->from($this->sessionTableName)
        ->where('expire>:expire AND id=:id',array(':expire'=>time(),':id'=>$id))
        ->queryScalar();
    return $data===false?'':$data;
}

public function regenerateID($deleteOldSession=false)
{
    $oldID=session_id();

    // if no session is started, there is nothing to regenerate
    if(empty($oldID))
        return;

    parent::regenerateID(false);
    $newID=session_id();
    $db=$this->getDbConnection();

    $row=$db->createCommand()
        ->select()
        ->from($this->sessionTableName)
        ->where('id=:id',array(':id'=>$oldID))
        ->queryRow();
    if($row!==false)
    {
        if($deleteOldSession)
            $db->createCommand()->update($this->sessionTableName,array(
                'id'=>$newID
            ),'id=:oldID',array(':oldID'=>$oldID));
        else
        {
            $row['id']=$newID;
            $db->createCommand()->insert($this->sessionTableName, $row);
        }
    }
    else
    {
        // shouldn't reach here normally
        $db->createCommand()->insert($this->sessionTableName, array(
            'id'=>$newID,
            'expire'=>time()+$this->getTimeout(),
            'data'=>'',
        ));
    }
}

public function writeSession($id,$data)
{
    // exception must be caught in session write handler
    // http://us.php.net/manual/en/function.session-set-save-handler.php
    try
    {
        $expire=time()+$this->getTimeout();
        $db=$this->getDbConnection();
        if($db->getDriverName()=='pgsql')
            $data=new CDbExpression($db->quoteValueWithType($data, PDO::PARAM_LOB)."::bytea");
        if($db->getDriverName()=='sqlsrv' || $db->getDriverName()=='mssql' || $db->getDriverName()=='dblib')
            $data=new CDbExpression('CONVERT(VARBINARY(MAX), '.$db->quoteValue($data).')');
        if($db->createCommand()->select('id')->from($this->sessionTableName)->where('id=:id',array(':id'=>$id))->queryScalar()===false)
            $db->createCommand()->insert($this->sessionTableName,array(
                'id'=>$id,
                'data'=>$data,
                'expire'=>$expire,
            ));
        else
            $db->createCommand()->update($this->sessionTableName,array(
                'data'=>$data,
                'expire'=>$expire
            ),'id=:id',array(':id'=>$id));
    }
    catch(Exception $e)
    {
        if(YII_DEBUG)
            echo $e->getMessage();
        // it is too late to log an error message here
        return false;
    }
    return true;
}