diff --git a/system/core/Common.php b/system/core/Common.php
index 225227d..4919793 100644
--- a/system/core/Common.php
+++ b/system/core/Common.php
@@ -56,7 +56,7 @@
 	function is_php($version = '5.0.0')
 	{
 		static $_is_php;
-		$version = (string)$version;
+		$version = (string) $version;
 
 		if ( ! isset($_is_php[$version]))
 		{
@@ -84,7 +84,7 @@
 	function is_really_writable($file)
 	{
 		// If we're on a Unix server with safe_mode off we call is_writable
-		if (DIRECTORY_SEPARATOR === '/' AND @ini_get('safe_mode') == FALSE)
+		if (DIRECTORY_SEPARATOR === '/' && (bool) @ini_get('safe_mode') === FALSE)
 		{
 			return is_writable($file);
 		}
@@ -120,7 +120,7 @@
 /**
 * Class registry
 *
-* This function acts as a singleton.  If the requested class does not
+* This function acts as a singleton. If the requested class does not
 * exist it is instantiated and set to a static variable.  If it has
 * previously been instantiated the variable is returned.
 *
@@ -192,7 +192,7 @@
 // --------------------------------------------------------------------
 
 /**
-* Keeps track of which libraries have been loaded.  This function is
+* Keeps track of which libraries have been loaded. This function is
 * called by the load_class() function above
 *
 * @access	public
@@ -437,7 +437,7 @@
 			show_error('Status codes must be numeric', 500);
 		}
 
-		if (isset($stati[$code]) AND $text == '')
+		if (isset($stati[$code]) && $text == '')
 		{
 			$text = $stati[$code];
 		}
@@ -447,19 +447,19 @@
 			show_error('No status text available. Please check your status code number or supply your own message text.', 500);
 		}
 
-		$server_protocol = (isset($_SERVER['SERVER_PROTOCOL'])) ? $_SERVER['SERVER_PROTOCOL'] : FALSE;
+		$server_protocol = isset($_SERVER['SERVER_PROTOCOL']) ? $_SERVER['SERVER_PROTOCOL'] : FALSE;
 
 		if (strpos(php_sapi_name(), 'cgi') === 0)
 		{
-			header("Status: {$code} {$text}", TRUE);
+			header('Status: '.$code.' '.$text, TRUE);
 		}
-		elseif ($server_protocol == 'HTTP/1.1' OR $server_protocol == 'HTTP/1.0')
+		elseif ($server_protocol === 'HTTP/1.0')
 		{
-			header($server_protocol." {$code} {$text}", TRUE, $code);
+			header('HTTP/1.0 '.$code.' '.$text, TRUE, $code);
 		}
 		else
 		{
-			header("HTTP/1.1 {$code} {$text}", TRUE, $code);
+			header('HTTP/1.1 '.$code.' '.$text, TRUE, $code);
 		}
 	}
 }
@@ -564,14 +564,9 @@
 {
 	function html_escape($var)
 	{
-		if (is_array($var))
-		{
-			return array_map('html_escape', $var);
-		}
-		else
-		{
-			return htmlspecialchars($var, ENT_QUOTES, config_item('charset'));
-		}
+		return is_array($var)
+			? array_map('html_escape', $var)
+			: htmlspecialchars($var, ENT_QUOTES, config_item('charset'));
 	}
 }
 
diff --git a/system/database/drivers/mssql/mssql_driver.php b/system/database/drivers/mssql/mssql_driver.php
index 2a10989..25a32f3 100644
--- a/system/database/drivers/mssql/mssql_driver.php
+++ b/system/database/drivers/mssql/mssql_driver.php
@@ -114,14 +114,25 @@
 	/**
 	 * Select the database
 	 *
-	 * @access	private called by the base class
-	 * @return	resource
+	 * @param	string	database name
+	 * @return	bool
 	 */
-	function db_select()
+	public function db_select($database = '')
 	{
+		if ($database === '')
+		{
+			$database = $this->database;
+		}
+
 		// Note: The brackets are required in the event that the DB name
 		// contains reserved characters
-		return @mssql_select_db('['.$this->database.']', $this->conn_id);
+		if (@mssql_select_db('['.$database.']', $this->conn_id))
+		{
+			$this->database = $database;
+			return TRUE;
+		}
+
+		return FALSE;
 	}
 
 	// --------------------------------------------------------------------
@@ -676,4 +687,4 @@
 
 
 /* End of file mssql_driver.php */
-/* Location: ./system/database/drivers/mssql/mssql_driver.php */
\ No newline at end of file
+/* Location: ./system/database/drivers/mssql/mssql_driver.php */
diff --git a/system/database/drivers/mysql/mysql_driver.php b/system/database/drivers/mysql/mysql_driver.php
index 067710f..c88a8a7 100644
--- a/system/database/drivers/mysql/mysql_driver.php
+++ b/system/database/drivers/mysql/mysql_driver.php
@@ -119,11 +119,23 @@
 	/**
 	 * Select the database
 	 *
+	 * @param	string	database name
 	 * @return	bool
 	 */
-	public function db_select()
+	public function db_select($database = '')
 	{
-		return @mysql_select_db($this->database, $this->conn_id);
+		if ($database === '')
+		{
+			$database = $this->database;
+		}
+
+		if (@mysql_select_db($database, $this->conn_id))
+		{
+			$this->database = $database;
+			return TRUE;
+		}
+
+		return FALSE;
 	}
 
 	// --------------------------------------------------------------------
diff --git a/system/database/drivers/mysqli/mysqli_driver.php b/system/database/drivers/mysqli/mysqli_driver.php
index a79b2a4..dbba12e 100644
--- a/system/database/drivers/mysqli/mysqli_driver.php
+++ b/system/database/drivers/mysqli/mysqli_driver.php
@@ -119,11 +119,23 @@
 	/**
 	 * Select the database
 	 *
+	 * @param	string	database name
 	 * @return	bool
 	 */
-	public function db_select()
+	public function db_select($database = '')
 	{
-		return @mysqli_select_db($this->conn_id, $this->database);
+		if ($database === '')
+		{
+			$database = $this->database;
+		}
+
+		if (@mysqli_select_db($this->conn_id, $database))
+		{
+			$this->database = $database;
+			return TRUE;
+		}
+
+		return FALSE;
 	}
 
 	// --------------------------------------------------------------------
diff --git a/system/database/drivers/sqlsrv/sqlsrv_driver.php b/system/database/drivers/sqlsrv/sqlsrv_driver.php
index 6fd52ef..9c50209 100644
--- a/system/database/drivers/sqlsrv/sqlsrv_driver.php
+++ b/system/database/drivers/sqlsrv/sqlsrv_driver.php
@@ -122,12 +122,23 @@
 	/**
 	 * Select the database
 	 *
-	 * @access	private called by the base class
-	 * @return	resource
+	 * @param	string	database name
+	 * @return	bool
 	 */
-	function db_select()
+	public function db_select($database = '')
 	{
-		return $this->_execute('USE ' . $this->database);
+		if ($database === '')
+		{
+			$database = $this->database;
+		}
+
+		if ($this->_execute('USE '.$database))
+		{
+			$this->database = $database;
+			return TRUE;
+		}
+
+		return FALSE;
 	}
 
 	// --------------------------------------------------------------------
@@ -608,4 +619,4 @@
 
 
 /* End of file mssql_driver.php */
-/* Location: ./system/database/drivers/mssql/mssql_driver.php */
\ No newline at end of file
+/* Location: ./system/database/drivers/mssql/mssql_driver.php */
diff --git a/system/libraries/Form_validation.php b/system/libraries/Form_validation.php
index 0a6a2af..2ee734a 100644
--- a/system/libraries/Form_validation.php
+++ b/system/libraries/Form_validation.php
@@ -703,11 +703,11 @@
 	 *
 	 * @param	string	the field name
 	 * @param	string
-	 * @return	void
+	 * @return	string
 	 */
 	public function set_value($field = '', $default = '')
 	{
-		if ( ! isset($this->_field_data[$field]))
+		if ( ! isset($this->_field_data[$field], $this->_field_data[$field]['postdata']))
 		{
 			return $default;
 		}
@@ -736,13 +736,9 @@
 	 */
 	public function set_select($field = '', $value = '', $default = FALSE)
 	{
-		if ( ! isset($this->_field_data[$field]) OR ! isset($this->_field_data[$field]['postdata']))
+		if ( ! isset($this->_field_data[$field], $this->_field_data[$field]['postdata']))
 		{
-			if ($default === TRUE AND count($this->_field_data) === 0)
-			{
-				return ' selected="selected"';
-			}
-			return '';
+			return ($default === TRUE && count($this->_field_data) === 0) ? ' selected="selected"' : '';
 		}
 
 		$field = $this->_field_data[$field]['postdata'];
@@ -754,12 +750,9 @@
 				return '';
 			}
 		}
-		else
+		elseif (($field == '' OR $value == '') OR ($field != $value))
 		{
-			if (($field == '' OR $value == '') OR ($field != $value))
-			{
-				return '';
-			}
+			return '';
 		}
 
 		return ' selected="selected"';
@@ -779,13 +772,9 @@
 	 */
 	public function set_radio($field = '', $value = '', $default = FALSE)
 	{
-		if ( ! isset($this->_field_data[$field]) OR ! isset($this->_field_data[$field]['postdata']))
+		if ( ! isset($this->_field_data[$field], $this->_field_data[$field]['postdata']))
 		{
-			if ($default === TRUE AND count($this->_field_data) === 0)
-			{
-				return ' checked="checked"';
-			}
-			return '';
+			return ($default === TRUE && count($this->_field_data) === 0) ? ' checked="checked"' : '';
 		}
 
 		$field = $this->_field_data[$field]['postdata'];
@@ -869,9 +858,7 @@
 			return FALSE;
 		}
 
-		$field = $_POST[$field];
-
-		return ($str === $field);
+		return ($str === $_POST[$field]);
 	}
 
 	// --------------------------------------------------------------------
@@ -908,7 +895,7 @@
 	 */
 	public function min_length($str, $val)
 	{
-		if (preg_match("/[^0-9]/", $val))
+		if (preg_match('/[^0-9]/', $val))
 		{
 			return FALSE;
 		}
@@ -932,7 +919,7 @@
 	 */
 	public function max_length($str, $val)
 	{
-		if (preg_match("/[^0-9]/", $val))
+		if (preg_match('/[^0-9]/', $val))
 		{
 			return FALSE;
 		}
@@ -956,7 +943,7 @@
 	 */
 	public function exact_length($str, $val)
 	{
-		if (preg_match("/[^0-9]/", $val))
+		if (preg_match('/[^0-9]/', $val))
 		{
 			return FALSE;
 		}
@@ -1170,7 +1157,7 @@
 	 */
 	public function is_natural_no_zero($str)
 	{
-		return ($str != 0 AND preg_match('/^[0-9]+$/', $str));
+		return ($str != 0 && preg_match('/^[0-9]+$/', $str));
 	}
 
 	// --------------------------------------------------------------------
@@ -1217,7 +1204,7 @@
 			return $data;
 		}
 
-		return str_replace(array("'", '"', '<', '>'), array("&#39;", "&quot;", '&lt;', '&gt;'), stripslashes($data));
+		return str_replace(array("'", '"', '<', '>'), array('&#39;', '&quot;', '&lt;', '&gt;'), stripslashes($data));
 	}
 
 	// --------------------------------------------------------------------
@@ -1283,7 +1270,6 @@
 	}
 
 }
-// END Form Validation Class
 
 /* End of file Form_validation.php */
 /* Location: ./system/libraries/Form_validation.php */
diff --git a/user_guide_src/source/changelog.rst b/user_guide_src/source/changelog.rst
index e926d50..c89aecd 100644
--- a/user_guide_src/source/changelog.rst
+++ b/user_guide_src/source/changelog.rst
@@ -51,6 +51,7 @@
    -  MySQLi driver now supports persistent connections when running on PHP >= 5.3.
    -  Added dsn if the group connections in the config use PDO or any driver which need DSN.
    -  Improved PDO database support.
+   -  An optional database name parameter was added db_select().
 
 -  Libraries
 
@@ -107,6 +108,7 @@
 -  Fixed a possible bug in ``CI_Input::is_ajax_request()`` where some clients might not send the X-Requested-With HTTP header value exactly as 'XmlHttpRequest'.
 -  Fixed a bug (#1039) - MySQL's _backup() method failed due to a table name not being escaped.
 -  Fixed a bug (#1070) - CI_DB_driver::initialize() didn't set a character set if a database is not selected.
+-  Fixed a bug (#177) - CI_Form_validation::set_value() didn't set the default value if POST data is NULL.
 -  Fixed a bug in CI_DB_driver::version() where it failed when using a database driver that needs to run a query in order to get the version.
 -  Fixed a bug (#1036) - Database method is_write_type() didn't match RENAME statements.
 
diff --git a/user_guide_src/source/database/connecting.rst b/user_guide_src/source/database/connecting.rst
index a834cc0..fb45241 100644
--- a/user_guide_src/source/database/connecting.rst
+++ b/user_guide_src/source/database/connecting.rst
@@ -122,6 +122,12 @@
 	| $DB1->result();
 	| etc...
 
+.. note:: You don't need to create separate database configurations if you
+	only need to use a different database on the same connection. You
+	can switch to a different database when you need to, like this:
+
+	| $this->db->db_select($database2_name);
+
 Reconnecting / Keeping the Connection Alive
 ===========================================