diff --git a/lib/Doctrine/DBAL/Driver/OCI8/Driver.php b/lib/Doctrine/DBAL/Driver/OCI8/Driver.php
index 4ff6d72d12d..ddba3bf94af 100644
--- a/lib/Doctrine/DBAL/Driver/OCI8/Driver.php
+++ b/lib/Doctrine/DBAL/Driver/OCI8/Driver.php
@@ -36,7 +36,9 @@ public function connect(array $params, $username = null, $password = null, array
         return new OCI8Connection(
             $username,
             $password,
-            $this->_constructDsn($params)
+            $this->_constructDsn($params),
+            isset($params['charset']) ? $params['charset'] : null,
+            isset($params['session_mode']) ? $params['session_mode'] : OCI_DEFAULT
         );
     }
 
@@ -67,10 +69,6 @@ private function _constructDsn(array $params)
             $dsn .= $params['dbname'];
         }
 
-        if (isset($params['charset'])) {
-            $dsn .= ';charset=' . $params['charset'];
-        }
-
         return $dsn;
     }
 
diff --git a/lib/Doctrine/DBAL/Driver/OCI8/OCI8Connection.php b/lib/Doctrine/DBAL/Driver/OCI8/OCI8Connection.php
index 987bf6c0c76..cfbb5962769 100644
--- a/lib/Doctrine/DBAL/Driver/OCI8/OCI8Connection.php
+++ b/lib/Doctrine/DBAL/Driver/OCI8/OCI8Connection.php
@@ -30,17 +30,19 @@ class OCI8Connection implements \Doctrine\DBAL\Driver\Connection
 {
     private $_dbh;
     
-    public function __construct($username, $password, $db)
+    private $_executionMode = OCI_COMMIT_ON_SUCCESS;
+    
+    public function __construct($username, $password, $db, $charset = null, $session_mode = OCI_DEFAULT)
     {
-        $this->_dbh = @oci_connect($username, $password, $db);
+        $this->_dbh = @oci_connect($username, $password, $db, $charset, $session_mode);
         if (!$this->_dbh) {
-            throw new OCI8Exception($this->errorInfo());
+            throw OCI8Exception::fromErrorInfo($this->errorInfo());
         }
     }
     
     public function prepare($prepareString)
     {
-        return new OCI8Statement($this->_dbh, $prepareString);
+        return new OCI8Statement($this, $prepareString);
     }
     
     public function query()
@@ -72,11 +74,13 @@ public function lastInsertId($name = null)
     
     public function beginTransaction()
     {
+        $this->_executionMode = OCI_NO_AUTO_COMMIT;
         return true;
     }
     
     public function commit()
     {
+        $this->_executionMode = OCI_COMMIT_ON_SUCCESS;
         if (!oci_commit($this->_dbh)) {
             throw OCI8Exception::fromErrorInfo($this->errorInfo());
         }
@@ -85,6 +89,7 @@ public function commit()
     
     public function rollBack()
     {
+        $this->_executionMode = OCI_COMMIT_ON_SUCCESS;
         if (!oci_rollback($this->_dbh)) {
             throw OCI8Exception::fromErrorInfo($this->errorInfo());
         }
@@ -93,7 +98,12 @@ public function rollBack()
     
     public function errorCode()
     {
-        $error = oci_error($this->_dbh);
+        if (!is_resource($this->_dbh)) {
+            $error = oci_error();
+        } else {
+            $error = oci_error($this->_dbh);
+        }
+        
         if ($error !== false) {
             $error = $error['code'];
         }
@@ -102,7 +112,20 @@ public function errorCode()
     
     public function errorInfo()
     {
+        if (!is_resource($this->_dbh)) {
+            return oci_error();
+        }
         return oci_error($this->_dbh);
     }
     
+    public function getDbh()
+    {
+        return $this->_dbh;
+    }
+    
+    public function getExecutionMode()
+    {
+        return $this->_executionMode;
+    }
+    
 }
\ No newline at end of file
diff --git a/lib/Doctrine/DBAL/Driver/OCI8/OCI8Statement.php b/lib/Doctrine/DBAL/Driver/OCI8/OCI8Statement.php
index d1168d12468..fdee78316f7 100644
--- a/lib/Doctrine/DBAL/Driver/OCI8/OCI8Statement.php
+++ b/lib/Doctrine/DBAL/Driver/OCI8/OCI8Statement.php
@@ -41,6 +41,7 @@ class OCI8Statement implements \Doctrine\DBAL\Driver\Statement
         PDO::FETCH_NUM => OCI_NUM
     );
     private $_paramMap = array();
+    private $_connection;
 
     /**
      * Creates a new OCI8Statement that uses the given connection handle and SQL statement.
@@ -48,9 +49,10 @@ class OCI8Statement implements \Doctrine\DBAL\Driver\Statement
      * @param resource $dbh The connection handle.
      * @param string $statement The SQL statement.
      */
-    public function __construct($dbh, $statement)
+    public function __construct($connection, $statement)
     {
-        $this->_sth = oci_parse($dbh, $this->_convertPositionalToNamedPlaceholders($statement));
+        $this->_connection = $connection;
+        $this->_sth = oci_parse($connection->getDbh(), $this->_convertPositionalToNamedPlaceholders($statement));
     }
 
     /**
@@ -146,7 +148,7 @@ public function execute($params = null)
             }
         }
 
-        $ret = @oci_execute($this->_sth, OCI_DEFAULT);
+        $ret = @oci_execute($this->_sth, $this->_connection->getExecutionMode());
         if ( ! $ret) {
             throw OCI8Exception::fromErrorInfo($this->errorInfo());
         }