Fix #4171 and a number of other transaction bugs

12 files changed, 71 insertions, 330 deletions

diff --git a/system/database/drivers/cubrid/cubrid_driver.php b/system/database/drivers/cubrid/cubrid_driver.php
index f80b4db54..65f4adb3f 100644
--- a/system/database/drivers/cubrid/cubrid_driver.php
+++ b/system/database/drivers/cubrid/cubrid_driver.php
@@ -187,25 +187,17 @@ class CI_DB_cubrid_driver extends CI_DB {
 	/**
 	 * Begin Transaction
 	 *
-	 * @param	bool	$test_mode
 	 * @return	bool
 	 */
-	public function trans_begin($test_mode = FALSE)
+	protected function _trans_begin()
 	{
-		// When transactions are nested we only begin/commit/rollback the outermost ones
-		if ( ! $this->trans_enabled OR $this->_trans_depth > 0)
+		if (($autocommit = cubrid_get_autocommit($this->conn_id)) === NULL)
 		{
-			return TRUE;
+			return FALSE;
 		}
-
-		// Reset the transaction failure flag.
-		// If the $test_mode flag is set to TRUE transactions will be rolled back
-		// even if the queries produce a successful result.
-		$this->_trans_failure = ($test_mode === TRUE);
-
-		if (cubrid_get_autocommit($this->conn_id))
+		elseif ($autocommit === TRUE)
 		{
-			cubrid_set_autocommit($this->conn_id, CUBRID_AUTOCOMMIT_FALSE);
+			return cubrid_set_autocommit($this->conn_id, CUBRID_AUTOCOMMIT_FALSE);
 		}
 
 		return TRUE;
@@ -218,19 +210,16 @@ class CI_DB_cubrid_driver extends CI_DB {
 	 *
 	 * @return	bool
 	 */
-	public function trans_commit()
+	protected function _trans_commit()
 	{
-		// When transactions are nested we only begin/commit/rollback the outermost ones
-		if ( ! $this->trans_enabled OR $this->_trans_depth > 0)
+		if ( ! cubrid_commit($this->conn_id))
 		{
-			return TRUE;
+			return FALSE;
 		}
 
-		cubrid_commit($this->conn_id);
-
 		if ($this->auto_commit && ! cubrid_get_autocommit($this->conn_id))
 		{
-			cubrid_set_autocommit($this->conn_id, CUBRID_AUTOCOMMIT_TRUE);
+			return cubrid_set_autocommit($this->conn_id, CUBRID_AUTOCOMMIT_TRUE);
 		}
 
 		return TRUE;
@@ -243,16 +232,13 @@ class CI_DB_cubrid_driver extends CI_DB {
 	 *
 	 * @return	bool
 	 */
-	public function trans_rollback()
+	protected function _trans_rollback()
 	{
-		// When transactions are nested we only begin/commit/rollback the outermost ones
-		if ( ! $this->trans_enabled OR $this->_trans_depth > 0)
+		if ( ! cubrid_rollback($this->conn_id))
 		{
-			return TRUE;
+			return FALSE;
 		}
 
-		cubrid_rollback($this->conn_id);
-
 		if ($this->auto_commit && ! cubrid_get_autocommit($this->conn_id))
 		{
 			cubrid_set_autocommit($this->conn_id, CUBRID_AUTOCOMMIT_TRUE);
diff --git a/system/database/drivers/ibase/ibase_driver.php b/system/database/drivers/ibase/ibase_driver.php
index 529c320cd..82550d51b 100644
--- a/system/database/drivers/ibase/ibase_driver.php
+++ b/system/database/drivers/ibase/ibase_driver.php
@@ -134,24 +134,16 @@ class CI_DB_ibase_driver extends CI_DB {
 	/**
 	 * Begin Transaction
 	 *
-	 * @param	bool	$test_mode
 	 * @return	bool
 	 */
-	public function trans_begin($test_mode = FALSE)
+	protected function _trans_begin()
 	{
-		// When transactions are nested we only begin/commit/rollback the outermost ones
-		if ( ! $this->trans_enabled OR $this->_trans_depth > 0)
+		if (($trans_handle = ibase_trans($this->conn_id)) === FALSE)
 		{
-			return TRUE;
+			return FALSE;
 		}
 
-		// Reset the transaction failure flag.
-		// If the $test_mode flag is set to TRUE transactions will be rolled back
-		// even if the queries produce a successful result.
-		$this->_trans_failure = ($test_mode === TRUE);
-
-		$this->_ibase_trans = ibase_trans($this->conn_id);
-
+		$this->_ibase_trans = $trans_handle;
 		return TRUE;
 	}
 
@@ -162,15 +154,15 @@ class CI_DB_ibase_driver extends CI_DB {
 	 *
 	 * @return	bool
 	 */
-	public function trans_commit()
+	protected function _trans_commit()
 	{
-		// When transactions are nested we only begin/commit/rollback the outermost ones
-		if ( ! $this->trans_enabled OR $this->_trans->depth > 0)
+		if (ibase_commit($this->_ibase_trans))
 		{
+			$this->_ibase_trans = NULL;
 			return TRUE;
 		}
 
-		return ibase_commit($this->_ibase_trans);
+		return FALSE;
 	}
 
 	// --------------------------------------------------------------------
@@ -180,15 +172,15 @@ class CI_DB_ibase_driver extends CI_DB {
 	 *
 	 * @return	bool
 	 */
-	public function trans_rollback()
+	protected function _trans_rollback()
 	{
-		// When transactions are nested we only begin/commit/rollback the outermost ones
-		if ( ! $this->trans_enabled OR $this->_trans_depth > 0)
+		if (ibase_rollback($this->_ibase_trans))
 		{
+			$this->_ibase_trans = NULL;
 			return TRUE;
 		}
 
-		return ibase_rollback($this->_ibase_trans);
+		return FALSE;
 	}
 
 	// --------------------------------------------------------------------
diff --git a/system/database/drivers/mssql/mssql_driver.php b/system/database/drivers/mssql/mssql_driver.php
index 05e5418c3..883973ae1 100644
--- a/system/database/drivers/mssql/mssql_driver.php
+++ b/system/database/drivers/mssql/mssql_driver.php
@@ -182,22 +182,10 @@ class CI_DB_mssql_driver extends CI_DB {
 	/**
 	 * Begin Transaction
 	 *
-	 * @param	bool	$test_mode
 	 * @return	bool
 	 */
-	public function trans_begin($test_mode = FALSE)
+	protected function _trans_begin()
 	{
-		// When transactions are nested we only begin/commit/rollback the outermost ones
-		if ( ! $this->trans_enabled OR $this->_trans_depth > 0)
-		{
-			return TRUE;
-		}
-
-		// Reset the transaction failure flag.
-		// If the $test_mode flag is set to TRUE transactions will be rolled back
-		// even if the queries produce a successful result.
-		$this->_trans_failure = ($test_mode === TRUE);
-
 		return $this->simple_query('BEGIN TRAN');
 	}
 
@@ -208,14 +196,8 @@ class CI_DB_mssql_driver extends CI_DB {
 	 *
 	 * @return	bool
 	 */
-	public function trans_commit()
+	protected function _trans_commit()
 	{
-		// When transactions are nested we only begin/commit/rollback the outermost ones
-		if ( ! $this->trans_enabled OR $this->_trans_depth > 0)
-		{
-			return TRUE;
-		}
-
 		return $this->simple_query('COMMIT TRAN');
 	}
 
@@ -226,14 +208,8 @@ class CI_DB_mssql_driver extends CI_DB {
 	 *
 	 * @return	bool
 	 */
-	public function trans_rollback()
+	protected function _trans_rollback()
 	{
-		// When transactions are nested we only begin/commit/rollback the outermost ones
-		if ( ! $this->trans_enabled OR $this->_trans_depth > 0)
-		{
-			return TRUE;
-		}
-
 		return $this->simple_query('ROLLBACK TRAN');
 	}
 
diff --git a/system/database/drivers/mysql/mysql_driver.php b/system/database/drivers/mysql/mysql_driver.php
index df0f24920..9c630d0d6 100644
--- a/system/database/drivers/mysql/mysql_driver.php
+++ b/system/database/drivers/mysql/mysql_driver.php
@@ -272,25 +272,12 @@ class CI_DB_mysql_driver extends CI_DB {
 	/**
 	 * Begin Transaction
 	 *
-	 * @param	bool	$test_mode
 	 * @return	bool
 	 */
-	public function trans_begin($test_mode = FALSE)
+	protected function _trans_begin()
 	{
-		// When transactions are nested we only begin/commit/rollback the outermost ones
-		if ( ! $this->trans_enabled OR $this->_trans_depth > 0)
-		{
-			return TRUE;
-		}
-
-		// Reset the transaction failure flag.
-		// If the $test_mode flag is set to TRUE transactions will be rolled back
-		// even if the queries produce a successful result.
-		$this->_trans_failure = ($test_mode === TRUE);
-
 		$this->simple_query('SET AUTOCOMMIT=0');
-		$this->simple_query('START TRANSACTION'); // can also be BEGIN or BEGIN WORK
-		return TRUE;
+		return $this->simple_query('START TRANSACTION'); // can also be BEGIN or BEGIN WORK
 	}
 
 	// --------------------------------------------------------------------
@@ -300,17 +287,15 @@ class CI_DB_mysql_driver extends CI_DB {
 	 *
 	 * @return	bool
 	 */
-	public function trans_commit()
+	protected function _trans_commit()
 	{
-		// When transactions are nested we only begin/commit/rollback the outermost ones
-		if ( ! $this->trans_enabled OR $this->_trans_depth > 0)
+		if ($this->simple_query('COMMIT'))
 		{
+			$this->simple_query('SET AUTOCOMMIT=1');
 			return TRUE;
 		}
 
-		$this->simple_query('COMMIT');
-		$this->simple_query('SET AUTOCOMMIT=1');
-		return TRUE;
+		return FALSE;
 	}
 
 	// --------------------------------------------------------------------
@@ -320,17 +305,15 @@ class CI_DB_mysql_driver extends CI_DB {
 	 *
 	 * @return	bool
 	 */
-	public function trans_rollback()
+	protected function _trans_rollback()
 	{
-		// When transactions are nested we only begin/commit/rollback the outermost ones
-		if ( ! $this->trans_enabled OR $this->_trans_depth > 0)
+		if ($this->simple_query('ROLLBACK'))
 		{
+			$this->simple_query('SET AUTOCOMMIT=1');
 			return TRUE;
 		}
 
-		$this->simple_query('ROLLBACK');
-		$this->simple_query('SET AUTOCOMMIT=1');
-		return TRUE;
+		return FALSE;
 	}
 
 	// --------------------------------------------------------------------
diff --git a/system/database/drivers/mysqli/mysqli_driver.php b/system/database/drivers/mysqli/mysqli_driver.php
index dd3cc77c6..827470078 100644
--- a/system/database/drivers/mysqli/mysqli_driver.php
+++ b/system/database/drivers/mysqli/mysqli_driver.php
@@ -291,22 +291,10 @@ class CI_DB_mysqli_driver extends CI_DB {
 	/**
 	 * Begin Transaction
 	 *
-	 * @param	bool	$test_mode
 	 * @return	bool
 	 */
-	public function trans_begin($test_mode = FALSE)
+	protected function _trans_begin()
 	{
-		// When transactions are nested we only begin/commit/rollback the outermost ones
-		if ( ! $this->trans_enabled OR $this->_trans_depth > 0)
-		{
-			return TRUE;
-		}
-
-		// Reset the transaction failure flag.
-		// If the $test_mode flag is set to TRUE transactions will be rolled back
-		// even if the queries produce a successful result.
-		$this->_trans_failure = ($test_mode === TRUE);
-
 		$this->conn_id->autocommit(FALSE);
 		return is_php('5.5')
 			? $this->conn_id->begin_transaction()
@@ -320,14 +308,8 @@ class CI_DB_mysqli_driver extends CI_DB {
 	 *
 	 * @return	bool
 	 */
-	public function trans_commit()
+	protected function _trans_commit()
 	{
-		// When transactions are nested we only begin/commit/rollback the outermost ones
-		if ( ! $this->trans_enabled OR $this->_trans_depth > 0)
-		{
-			return TRUE;
-		}
-
 		if ($this->conn_id->commit())
 		{
 			$this->conn_id->autocommit(TRUE);
@@ -344,14 +326,8 @@ class CI_DB_mysqli_driver extends CI_DB {
 	 *
 	 * @return	bool
 	 */
-	public function trans_rollback()
+	protected function _trans_rollback()
 	{
-		// When transactions are nested we only begin/commit/rollback the outermost ones
-		if ( ! $this->trans_enabled OR $this->_trans_depth > 0)
-		{
-			return TRUE;
-		}
-
 		if ($this->conn_id->rollback())
 		{
 			$this->conn_id->autocommit(TRUE);
diff --git a/system/database/drivers/oci8/oci8_driver.php b/system/database/drivers/oci8/oci8_driver.php
index f2e40da9b..916ddeb90 100644
--- a/system/database/drivers/oci8/oci8_driver.php
+++ b/system/database/drivers/oci8/oci8_driver.php
@@ -378,27 +378,10 @@ class CI_DB_oci8_driver extends CI_DB {
 	/**
 	 * Begin Transaction
 	 *
-	 * @param	bool	$test_mode
 	 * @return	bool
 	 */
-	public function trans_begin($test_mode = FALSE)
+	protected function _trans_begin()
 	{
-		if ( ! $this->trans_enabled)
-		{
-			return TRUE;
-		}
-
-		// When transactions are nested we only begin/commit/rollback the outermost ones
-		if ($this->_trans_depth > 0)
-		{
-			return TRUE;
-		}
-
-		// Reset the transaction failure flag.
-		// If the $test_mode flag is set to TRUE transactions will be rolled back
-		// even if the queries produce a successful result.
-		$this->_trans_failure = ($test_mode === TRUE);
-
 		$this->commit_mode = is_php('5.3.2') ? OCI_NO_AUTO_COMMIT : OCI_DEFAULT;
 		return TRUE;
 	}
@@ -410,20 +393,10 @@ class CI_DB_oci8_driver extends CI_DB {
 	 *
 	 * @return	bool
 	 */
-	public function trans_commit()
+	protected function _trans_commit()
 	{
-		if ( ! $this->trans_enabled)
-		{
-			return TRUE;
-		}
-
-		// When transactions are nested we only begin/commit/rollback the outermost ones
-		if ($this->_trans_depth > 0)
-		{
-			return TRUE;
-		}
-
 		$this->commit_mode = OCI_COMMIT_ON_SUCCESS;
+
 		return oci_commit($this->conn_id);
 	}
 
@@ -434,14 +407,8 @@ class CI_DB_oci8_driver extends CI_DB {
 	 *
 	 * @return	bool
 	 */
-	public function trans_rollback()
+	protected function _trans_rollback()
 	{
-		// When transactions are nested we only begin/commit/rollback the outermost ones
-		if ( ! $this->trans_enabled OR $this->_trans_depth > 0)
-		{
-			return TRUE;
-		}
-
 		$this->commit_mode = OCI_COMMIT_ON_SUCCESS;
 		return oci_rollback($this->conn_id);
 	}
diff --git a/system/database/drivers/odbc/odbc_driver.php b/system/database/drivers/odbc/odbc_driver.php
index f5d77a147..409284b44 100644
--- a/system/database/drivers/odbc/odbc_driver.php
+++ b/system/database/drivers/odbc/odbc_driver.php
@@ -143,22 +143,10 @@ class CI_DB_odbc_driver extends CI_DB {
 	/**
 	 * Begin Transaction
 	 *
-	 * @param	bool	$test_mode
 	 * @return	bool
 	 */
-	public function trans_begin($test_mode = FALSE)
+	protected function _trans_begin()
 	{
-		// When transactions are nested we only begin/commit/rollback the outermost ones
-		if ( ! $this->trans_enabled OR $this->_trans_depth > 0)
-		{
-			return TRUE;
-		}
-
-		// Reset the transaction failure flag.
-		// If the $test_mode flag is set to TRUE transactions will be rolled back
-		// even if the queries produce a successful result.
-		$this->_trans_failure = ($test_mode === TRUE);
-
 		return odbc_autocommit($this->conn_id, FALSE);
 	}
 
@@ -169,17 +157,15 @@ class CI_DB_odbc_driver extends CI_DB {
 	 *
 	 * @return	bool
 	 */
-	public function trans_commit()
+	protected function _trans_commit()
 	{
-		// When transactions are nested we only begin/commit/rollback the outermost ones
-		if ( ! $this->trans_enabled OR $this->_trans_depth > 0)
+		if (odbc_commit($this->conn_id))
 		{
+			odbc_autocommit($this->conn_id, TRUE);
 			return TRUE;
 		}
 
-		$ret = odbc_commit($this->conn_id);
-		odbc_autocommit($this->conn_id, TRUE);
-		return $ret;
+		return FALSE;
 	}
 
 	// --------------------------------------------------------------------
@@ -189,17 +175,15 @@ class CI_DB_odbc_driver extends CI_DB {
 	 *
 	 * @return	bool
 	 */
-	public function trans_rollback()
+	protected function _trans_rollback()
 	{
-		// When transactions are nested we only begin/commit/rollback the outermost ones
-		if ( ! $this->trans_enabled OR $this->_trans_depth > 0)
+		if (odbc_rollback($this->conn_id))
 		{
+			odbc_autocommit($this->conn_id, TRUE);
 			return TRUE;
 		}
 
-		$ret = odbc_rollback($this->conn_id);
-		odbc_autocommit($this->conn_id, TRUE);
-		return $ret;
+		return FALSE;
 	}
 
 	// --------------------------------------------------------------------
diff --git a/system/database/drivers/pdo/pdo_driver.php b/system/database/drivers/pdo/pdo_driver.php
index cc77e9568..8c5a5e7e3 100644
--- a/system/database/drivers/pdo/pdo_driver.php
+++ b/system/database/drivers/pdo/pdo_driver.php
@@ -186,22 +186,10 @@ class CI_DB_pdo_driver extends CI_DB {
 	/**
 	 * Begin Transaction
 	 *
-	 * @param	bool	$test_mode
 	 * @return	bool
 	 */
-	public function trans_begin($test_mode = FALSE)
+	protected function _trans_begin()
 	{
-		// When transactions are nested we only begin/commit/rollback the outermost ones
-		if ( ! $this->trans_enabled OR $this->_trans_depth > 0)
-		{
-			return TRUE;
-		}
-
-		// Reset the transaction failure flag.
-		// If the $test_mode flag is set to TRUE transactions will be rolled back
-		// even if the queries produce a successful result.
-		$this->_trans_failure = ($test_mode === TRUE);
-
 		return $this->conn_id->beginTransaction();
 	}
 
@@ -212,14 +200,8 @@ class CI_DB_pdo_driver extends CI_DB {
 	 *
 	 * @return	bool
 	 */
-	public function trans_commit()
+	protected function _trans_commit()
 	{
-		// When transactions are nested we only begin/commit/rollback the outermost ones
-		if ( ! $this->trans_enabled OR $this->_trans_depth > 0)
-		{
-			return TRUE;
-		}
-
 		return $this->conn_id->commit();
 	}
 
@@ -230,14 +212,8 @@ class CI_DB_pdo_driver extends CI_DB {
 	 *
 	 * @return	bool
 	 */
-	public function trans_rollback()
+	protected function _trans_rollback()
 	{
-		// When transactions are nested we only begin/commit/rollback the outermost ones
-		if ( ! $this->trans_enabled OR $this->_trans_depth > 0)
-		{
-			return TRUE;
-		}
-
 		return $this->conn_id->rollBack();
 	}
 
diff --git a/system/database/drivers/postgre/postgre_driver.php b/system/database/drivers/postgre/postgre_driver.php
index 7be07c3bf..b1df326f7 100644
--- a/system/database/drivers/postgre/postgre_driver.php
+++ b/system/database/drivers/postgre/postgre_driver.php
@@ -247,22 +247,10 @@ class CI_DB_postgre_driver extends CI_DB {
 	/**
 	 * Begin Transaction
 	 *
-	 * @param	bool	$test_mode
 	 * @return	bool
 	 */
-	public function trans_begin($test_mode = FALSE)
+	protected function _trans_begin()
 	{
-		// When transactions are nested we only begin/commit/rollback the outermost ones
-		if ( ! $this->trans_enabled OR $this->_trans_depth > 0)
-		{
-			return TRUE;
-		}
-
-		// Reset the transaction failure flag.
-		// If the $test_mode flag is set to TRUE transactions will be rolled back
-		// even if the queries produce a successful result.
-		$this->_trans_failure = ($test_mode === TRUE);
-
 		return (bool) pg_query($this->conn_id, 'BEGIN');
 	}
 
@@ -273,14 +261,8 @@ class CI_DB_postgre_driver extends CI_DB {
 	 *
 	 * @return	bool
 	 */
-	public function trans_commit()
+	protected function _trans_commit()
 	{
-		// When transactions are nested we only begin/commit/rollback the outermost ones
-		if ( ! $this->trans_enabled OR $this->_trans_depth > 0)
-		{
-			return TRUE;
-		}
-
 		return (bool) pg_query($this->conn_id, 'COMMIT');
 	}
 
@@ -291,14 +273,8 @@ class CI_DB_postgre_driver extends CI_DB {
 	 *
 	 * @return	bool
 	 */
-	public function trans_rollback()
+	protected function _trans_rollback()
 	{
-		// When transactions are nested we only begin/commit/rollback the outermost ones
-		if ( ! $this->trans_enabled OR $this->_trans_depth > 0)
-		{
-			return TRUE;
-		}
-
 		return (bool) pg_query($this->conn_id, 'ROLLBACK');
 	}
 
diff --git a/system/database/drivers/sqlite/sqlite_driver.php b/system/database/drivers/sqlite/sqlite_driver.php
index 9d9caa0b4..e000a8e50 100644
--- a/system/database/drivers/sqlite/sqlite_driver.php
+++ b/system/database/drivers/sqlite/sqlite_driver.php
@@ -122,24 +122,11 @@ class CI_DB_sqlite_driver extends CI_DB {
 	/**
 	 * Begin Transaction
 	 *
-	 * @param	bool	$test_mode
 	 * @return	bool
 	 */
-	public function trans_begin($test_mode = FALSE)
+	protected function _trans_begin()
 	{
-		// When transactions are nested we only begin/commit/rollback the outermost ones
-		if ( ! $this->trans_enabled OR $this->_trans_depth > 0)
-		{
-			return TRUE;
-		}
-
-		// Reset the transaction failure flag.
-		// If the $test_mode flag is set to TRUE transactions will be rolled back
-		// even if the queries produce a successful result.
-		$this->_trans_failure = ($test_mode === TRUE);
-
-		$this->simple_query('BEGIN TRANSACTION');
-		return TRUE;
+		return $this->simple_query('BEGIN TRANSACTION');
 	}
 
 	// --------------------------------------------------------------------
@@ -149,16 +136,9 @@ class CI_DB_sqlite_driver extends CI_DB {
 	 *
 	 * @return	bool
 	 */
-	public function trans_commit()
+	protected function _trans_commit()
 	{
-		// When transactions are nested we only begin/commit/rollback the outermost ones
-		if ( ! $this->trans_enabled OR $this->_trans_depth > 0)
-		{
-			return TRUE;
-		}
-
-		$this->simple_query('COMMIT');
-		return TRUE;
+		return $this->simple_query('COMMIT');
 	}
 
 	// --------------------------------------------------------------------
@@ -168,16 +148,9 @@ class CI_DB_sqlite_driver extends CI_DB {
 	 *
 	 * @return	bool
 	 */
-	public function trans_rollback()
+	protected function _trans_rollback()
 	{
-		// When transactions are nested we only begin/commit/rollback the outermost ones
-		if ( ! $this->trans_enabled OR $this->_trans_depth > 0)
-		{
-			return TRUE;
-		}
-
-		$this->simple_query('ROLLBACK');
-		return TRUE;
+		return $this->simple_query('ROLLBACK');
 	}
 
 	// --------------------------------------------------------------------
diff --git a/system/database/drivers/sqlite3/sqlite3_driver.php b/system/database/drivers/sqlite3/sqlite3_driver.php
index 31e37de91..73e453785 100644
--- a/system/database/drivers/sqlite3/sqlite3_driver.php
+++ b/system/database/drivers/sqlite3/sqlite3_driver.php
@@ -134,22 +134,10 @@ class CI_DB_sqlite3_driver extends CI_DB {
 	/**
 	 * Begin Transaction
 	 *
-	 * @param	bool	$test_mode
 	 * @return	bool
 	 */
-	public function trans_begin($test_mode = FALSE)
+	protected function _trans_begin()
 	{
-		// When transactions are nested we only begin/commit/rollback the outermost ones
-		if ( ! $this->trans_enabled OR $this->_trans_depth > 0)
-		{
-			return TRUE;
-		}
-
-		// Reset the transaction failure flag.
-		// If the $test_mode flag is set to TRUE transactions will be rolled back
-		// even if the queries produce a successful result.
-		$this->_trans_failure = ($test_mode === TRUE);
-
 		return $this->conn_id->exec('BEGIN TRANSACTION');
 	}
 
@@ -160,14 +148,8 @@ class CI_DB_sqlite3_driver extends CI_DB {
 	 *
 	 * @return	bool
 	 */
-	public function trans_commit()
+	protected function _trans_commit()
 	{
-		// When transactions are nested we only begin/commit/rollback the outermost ones
-		if ( ! $this->trans_enabled OR $this->_trans_depth > 0)
-		{
-			return TRUE;
-		}
-
 		return $this->conn_id->exec('END TRANSACTION');
 	}
 
@@ -178,14 +160,8 @@ class CI_DB_sqlite3_driver extends CI_DB {
 	 *
 	 * @return	bool
 	 */
-	public function trans_rollback()
+	protected function _trans_rollback()
 	{
-		// When transactions are nested we only begin/commit/rollback the outermost ones
-		if ( ! $this->trans_enabled OR $this->_trans_depth > 0)
-		{
-			return TRUE;
-		}
-
 		return $this->conn_id->exec('ROLLBACK');
 	}
 
diff --git a/system/database/drivers/sqlsrv/sqlsrv_driver.php b/system/database/drivers/sqlsrv/sqlsrv_driver.php
index 1df3a4258..414669a4b 100644
--- a/system/database/drivers/sqlsrv/sqlsrv_driver.php
+++ b/system/database/drivers/sqlsrv/sqlsrv_driver.php
@@ -197,22 +197,10 @@ class CI_DB_sqlsrv_driver extends CI_DB {
 	/**
 	 * Begin Transaction
 	 *
-	 * @param	bool	$test_mode
 	 * @return	bool
 	 */
-	public function trans_begin($test_mode = FALSE)
+	protected function _trans_begin()
 	{
-		// When transactions are nested we only begin/commit/rollback the outermost ones
-		if ( ! $this->trans_enabled OR $this->_trans_depth > 0)
-		{
-			return TRUE;
-		}
-
-		// Reset the transaction failure flag.
-		// If the $test_mode flag is set to TRUE transactions will be rolled back
-		// even if the queries produce a successful result.
-		$this->_trans_failure = ($test_mode === TRUE);
-
 		return sqlsrv_begin_transaction($this->conn_id);
 	}
 
@@ -223,14 +211,8 @@ class CI_DB_sqlsrv_driver extends CI_DB {
 	 *
 	 * @return	bool
 	 */
-	public function trans_commit()
+	protected function _trans_commit()
 	{
-		// When transactions are nested we only begin/commit/rollback the outermost ones
-		if ( ! $this->trans_enabled OR $this->_trans_depth > 0)
-		{
-			return TRUE;
-		}
-
 		return sqlsrv_commit($this->conn_id);
 	}
 
@@ -241,14 +223,8 @@ class CI_DB_sqlsrv_driver extends CI_DB {
 	 *
 	 * @return	bool
 	 */
-	public function trans_rollback()
+	protected function _trans_rollback()
 	{
-		// When transactions are nested we only begin/commit/rollback the outermost ones
-		if ( ! $this->trans_enabled OR $this->_trans_depth > 0)
-		{
-			return TRUE;
-		}
-
 		return sqlsrv_rollback($this->conn_id);
 	}