Resolve _protect_identifiers()/protect_identifiers() usage issues
diff --git a/system/database/drivers/pdo/pdo_forge.php b/system/database/drivers/pdo/pdo_forge.php
index 478b2db..b4ddca5 100644
--- a/system/database/drivers/pdo/pdo_forge.php
+++ b/system/database/drivers/pdo/pdo_forge.php
@@ -113,7 +113,7 @@
 				$attributes = array_change_key_case($attributes, CASE_UPPER);
 				$numeric    = array('SERIAL', 'INTEGER');
 
-				$sql .= "\n\t".$this->db->_protect_identifiers($field);
+				$sql .= "\n\t".$this->db->protect_identifiers($field);
 
 				$sql .=  ' '.$attributes['TYPE'];
 
@@ -160,7 +160,7 @@
 
 		if (count($primary_keys) > 0)
 		{
-			$primary_keys = $this->db->_protect_identifiers($primary_keys);
+			$primary_keys = $this->db->protect_identifiers($primary_keys);
 			$sql .= ",\n\tPRIMARY KEY (" . implode(', ', $primary_keys) . ")";
 		}
 
@@ -170,11 +170,11 @@
 			{
 				if (is_array($key))
 				{
-					$key = $this->db->_protect_identifiers($key);
+					$key = $this->db->protect_identifiers($key);
 				}
 				else
 				{
-					$key = array($this->db->_protect_identifiers($key));
+					$key = array($this->db->protect_identifiers($key));
 				}
 
 				$sql .= ",\n\tFOREIGN KEY (" . implode(', ', $key) . ")";
@@ -224,7 +224,7 @@
 	 */
 	function _alter_table($alter_type, $table, $column_name, $column_definition = '', $default_value = '', $null = '', $after_field = '')
 	{
-		$sql = 'ALTER TABLE `'.$this->db->_protect_identifiers($table)."` $alter_type ".$this->db->_protect_identifiers($column_name);
+		$sql = 'ALTER TABLE `'.$this->db->protect_identifiers($table).'` '.$alter_type.' '.$this->db->protect_identifiers($column_name);
 
 		// DROP has everything it needs now.
 		if ($alter_type == 'DROP')
@@ -250,7 +250,7 @@
 
 		if ($after_field != '')
 		{
-			$sql .= ' AFTER ' . $this->db->_protect_identifiers($after_field);
+			return $sql.' AFTER '.$this->db->protect_identifiers($after_field);
 		}
 
 		return $sql;
@@ -272,11 +272,10 @@
 	 */
 	function _rename_table($table_name, $new_table_name)
 	{
-		$sql = 'ALTER TABLE '.$this->db->_protect_identifiers($table_name)." RENAME TO ".$this->db->_protect_identifiers($new_table_name);
-		return $sql;
+		return 'ALTER TABLE '.$this->db->protect_identifiers($table_name).' RENAME TO '.$this->db->protect_identifiers($new_table_name);
 	}
 
 }
 
 /* End of file pdo_forge.php */
-/* Location: ./system/database/drivers/pdo/pdo_forge.php */
\ No newline at end of file
+/* Location: ./system/database/drivers/pdo/pdo_forge.php */