Add a note to the num_rows() documentation
diff --git a/user_guide_src/source/database/results.rst b/user_guide_src/source/database/results.rst
index 4f93c79..90d2efc 100644
--- a/user_guide_src/source/database/results.rst
+++ b/user_guide_src/source/database/results.rst
@@ -150,6 +150,12 @@
 	
 	echo $query->num_rows();
 
+..note::
+	Not all database drivers have a native way of getting the total
+	number of rows for a result set. When this is the case, all of
+	the data is prefetched and count() is manually called on the
+	resulting array in order to achieve the same functionality.
+	
 $query->num_fields()
 =====================
 
@@ -182,5 +188,4 @@
 
 	$row = $query2->row();
 	echo $row->name;
-	$query2->free_result();// The $query2 result object will no longer be available
-
+	$query2->free_result(); // The $query2 result object will no longer be available