diff --git a/system/database/DB_driver.php b/system/database/DB_driver.php
index 09273ba..7da4b1a 100644
--- a/system/database/DB_driver.php
+++ b/system/database/DB_driver.php
@@ -185,20 +185,19 @@
 	/**
 	 * Set client character set
 	 *
-	 * @access	public
 	 * @param	string
 	 * @param	string
-	 * @return	resource
+	 * @return	bool
 	 */
-	function db_set_charset($charset, $collation)
+	public function db_set_charset($charset, $collation = '')
 	{
-		if ( ! $this->_db_set_charset($this->char_set, $this->dbcollat))
+		if (method_exists($this, '_db_set_charset') && ! $this->_db_set_charset($charset, $collation))
 		{
-			log_message('error', 'Unable to set database connection charset: '.$this->char_set);
+			log_message('error', 'Unable to set database connection charset: '.$charset);
 
 			if ($this->db_debug)
 			{
-				$this->display_error('db_unable_to_set_charset', $this->char_set);
+				$this->display_error('db_unable_to_set_charset', $charset);
 			}
 
 			return FALSE;
diff --git a/system/database/drivers/cubrid/cubrid_driver.php b/system/database/drivers/cubrid/cubrid_driver.php
index cde719e..42f08fb 100644
--- a/system/database/drivers/cubrid/cubrid_driver.php
+++ b/system/database/drivers/cubrid/cubrid_driver.php
@@ -156,24 +156,6 @@
 	// --------------------------------------------------------------------
 
 	/**
-	 * Set client character set
-	 *
-	 * @access	public
-	 * @param	string
-	 * @param	string
-	 * @return	resource
-	 */
-	function db_set_charset($charset, $collation)
-	{
-		// In CUBRID, there is no need to set charset or collation.
-		// This is why returning true will allow the application continue
-		// its normal process.
-		return TRUE;
-	}
-
-	// --------------------------------------------------------------------
-
-	/**
 	 * Version number query string
 	 *
 	 * @access	public
@@ -362,12 +344,11 @@
 	/**
 	 * Affected Rows
 	 *
-	 * @access	public
-	 * @return	integer
+	 * @return	int
 	 */
-	function affected_rows()
+	public function affected_rows()
 	{
-		return @cubrid_affected_rows($this->conn_id);
+		return @cubrid_affected_rows();
 	}
 
 	// --------------------------------------------------------------------
@@ -801,4 +782,4 @@
 
 
 /* End of file cubrid_driver.php */
-/* Location: ./system/database/drivers/cubrid/cubrid_driver.php */
\ No newline at end of file
+/* Location: ./system/database/drivers/cubrid/cubrid_driver.php */
diff --git a/system/database/drivers/mssql/mssql_driver.php b/system/database/drivers/mssql/mssql_driver.php
index 25a32f3..2a4f2b5 100644
--- a/system/database/drivers/mssql/mssql_driver.php
+++ b/system/database/drivers/mssql/mssql_driver.php
@@ -138,22 +138,6 @@
 	// --------------------------------------------------------------------
 
 	/**
-	 * Set client character set
-	 *
-	 * @access	public
-	 * @param	string
-	 * @param	string
-	 * @return	resource
-	 */
-	function db_set_charset($charset, $collation)
-	{
-		// @todo - add support if needed
-		return TRUE;
-	}
-
-	// --------------------------------------------------------------------
-
-	/**
 	 * Execute the query
 	 *
 	 * @access	private called by the base class
diff --git a/system/database/drivers/oci8/oci8_driver.php b/system/database/drivers/oci8/oci8_driver.php
index 057095c..d9acaae 100644
--- a/system/database/drivers/oci8/oci8_driver.php
+++ b/system/database/drivers/oci8/oci8_driver.php
@@ -139,22 +139,6 @@
 	// --------------------------------------------------------------------
 
 	/**
-	 * Set client character set
-	 *
-	 * @access	public
-	 * @param	string
-	 * @param	string
-	 * @return	resource
-	 */
-	public function db_set_charset($charset, $collation)
-	{
-		// this is done upon connect
-		return TRUE;
-	}
-
-	// --------------------------------------------------------------------
-
-	/**
 	 * Version number query string
 	 *
 	 * @access  protected
diff --git a/system/database/drivers/odbc/odbc_driver.php b/system/database/drivers/odbc/odbc_driver.php
index 6ba39f0..abb6603 100644
--- a/system/database/drivers/odbc/odbc_driver.php
+++ b/system/database/drivers/odbc/odbc_driver.php
@@ -124,22 +124,6 @@
 	// --------------------------------------------------------------------
 
 	/**
-	 * Set client character set
-	 *
-	 * @access	public
-	 * @param	string
-	 * @param	string
-	 * @return	resource
-	 */
-	function db_set_charset($charset, $collation)
-	{
-		// @todo - add support if needed
-		return TRUE;
-	}
-
-	// --------------------------------------------------------------------
-
-	/**
 	 * Version number query string
 	 *
 	 * @access	public
@@ -646,4 +630,4 @@
 
 
 /* End of file odbc_driver.php */
-/* Location: ./system/database/drivers/odbc/odbc_driver.php */
\ No newline at end of file
+/* Location: ./system/database/drivers/odbc/odbc_driver.php */
diff --git a/system/database/drivers/pdo/pdo_driver.php b/system/database/drivers/pdo/pdo_driver.php
index 44e93a0..90f0fd7 100644
--- a/system/database/drivers/pdo/pdo_driver.php
+++ b/system/database/drivers/pdo/pdo_driver.php
@@ -289,21 +289,6 @@
 	// --------------------------------------------------------------------
 
 	/**
-	 * Set client character set
-	 *
-	 * @access	public
-	 * @param	string
-	 * @param	string
-	 * @return	resource
-	 */
-	function db_set_charset($charset, $collation)
-	{
-		return TRUE;
-	}
-
-	// --------------------------------------------------------------------
-
-	/**
 	 * Version number query string
 	 *
 	 * @return	string
@@ -509,33 +494,19 @@
 
 	/**
 	 * Insert ID
-	 * 
-	 * @access	public
-	 * @return	integer
+	 *
+	 * @return	int
 	 */
-	function insert_id($name=NULL)
+	public function insert_id($name = NULL)
 	{
-		if ($this->pdodriver == 'pgsql')
+		if ($this->pdodriver === 'pgsql' && $name === NULL && $this->_version() >= '8.1')
 		{
-			//Convenience method for postgres insertid
-			$v = $this->_version();
-
-			$table	= func_num_args() > 0 ? func_get_arg(0) : NULL;
-
-			if ($table == NULL && $v >= '8.1')
-			{
-				$sql='SELECT LASTVAL() as ins_id';
-			}
-
-			$query = $this->query($sql);
-			$row   = $query->row();
-
-			return $row->ins_id;
+			$query = $this->query('SELECT LASTVAL() AS ins_id');
+			$query = $query->row();
+			return $query->ins_id;
 		}
-		else
-		{
-			return $this->conn_id->lastInsertId($name);
-		}
+
+		return $this->conn_id->lastInsertId($name);
 	}
 
 	// --------------------------------------------------------------------
diff --git a/system/database/drivers/postgre/postgre_driver.php b/system/database/drivers/postgre/postgre_driver.php
index 42329bd..89541e5 100644
--- a/system/database/drivers/postgre/postgre_driver.php
+++ b/system/database/drivers/postgre/postgre_driver.php
@@ -147,22 +147,6 @@
 	// --------------------------------------------------------------------
 
 	/**
-	 * Set client character set
-	 *
-	 * @access	public
-	 * @param	string
-	 * @param	string
-	 * @return	resource
-	 */
-	function db_set_charset($charset, $collation)
-	{
-		// @todo - add support if needed
-		return TRUE;
-	}
-
-	// --------------------------------------------------------------------
-
-	/**
 	 * Version number query string
 	 *
 	 * @access	public
@@ -712,4 +696,4 @@
 
 
 /* End of file postgre_driver.php */
-/* Location: ./system/database/drivers/postgre/postgre_driver.php */
\ No newline at end of file
+/* Location: ./system/database/drivers/postgre/postgre_driver.php */
diff --git a/system/database/drivers/sqlite/sqlite_driver.php b/system/database/drivers/sqlite/sqlite_driver.php
index 28c3cae..718501b 100644
--- a/system/database/drivers/sqlite/sqlite_driver.php
+++ b/system/database/drivers/sqlite/sqlite_driver.php
@@ -141,22 +141,6 @@
 	// --------------------------------------------------------------------
 
 	/**
-	 * Set client character set
-	 *
-	 * @access	public
-	 * @param	string
-	 * @param	string
-	 * @return	resource
-	 */
-	function db_set_charset($charset, $collation)
-	{
-		// @todo - add support if needed
-		return TRUE;
-	}
-
-	// --------------------------------------------------------------------
-
-	/**
 	 * Version number query string
 	 *
 	 * @access	public
@@ -667,4 +651,4 @@
 
 
 /* End of file sqlite_driver.php */
-/* Location: ./system/database/drivers/sqlite/sqlite_driver.php */
\ No newline at end of file
+/* Location: ./system/database/drivers/sqlite/sqlite_driver.php */
diff --git a/system/database/drivers/sqlsrv/sqlsrv_driver.php b/system/database/drivers/sqlsrv/sqlsrv_driver.php
index e4fd902..9b90381 100644
--- a/system/database/drivers/sqlsrv/sqlsrv_driver.php
+++ b/system/database/drivers/sqlsrv/sqlsrv_driver.php
@@ -144,22 +144,6 @@
 	// --------------------------------------------------------------------
 
 	/**
-	 * Set client character set
-	 *
-	 * @access	public
-	 * @param	string
-	 * @param	string
-	 * @return	resource
-	 */
-	function db_set_charset($charset, $collation)
-	{
-		// @todo - add support if needed
-		return TRUE;
-	}
-
-	// --------------------------------------------------------------------
-
-	/**
 	 * Execute the query
 	 *
 	 * @access	private called by the base class
diff --git a/user_guide_src/source/changelog.rst b/user_guide_src/source/changelog.rst
index 51a4515..41ee28b 100644
--- a/user_guide_src/source/changelog.rst
+++ b/user_guide_src/source/changelog.rst
@@ -120,6 +120,9 @@
 -  Fixed a bug (#611) - SQLSRV's _error_message() and _error_number() methods used to issue warnings when there's no actual error.
 -  Fixed a bug (#1036) - is_write_type() method in the :doc:`Database Library <database/index>` didn't return TRUE for RENAME and OPTIMIZE queries.
 -  Fixed a bug in PDO's _version() method where it used to return the client version as opposed to the server one.
+-  Fixed a bug in PDO's insert_id() method where it could've failed if it's used with Postgre versions prior to 8.1.
+-  Fixed a bug in CUBRID's affected_rows() method where a connection resource was passed to cubrid_affected_rows() instead of a result.
+-  Fixed a bug (#638) - db_set_charset() ignored its arguments and always used the configured charset and collation instead.
 
 Version 2.1.1
 =============
@@ -141,7 +144,6 @@
 -  Fixed a bug - CI_Upload::_file_mime_type() could've failed if mime_content_type() is used for the detection and returns FALSE.
 -  Fixed a bug (#538) - Windows paths were ignored when using the :doc:`Image Manipulation Library <libraries/image_lib>` to create a new file.
 
-
 Version 2.1.0
 =============