diff --git a/docs/examples/csharp/SQLInsertExample.cs b/docs/examples/csharp/SQLInsertExample.cs
index 192ea96d5713bbf7f37f2208687c41e3e66d473b..3ce70fe9144d997b320610500be29b329b69a08f 100644
--- a/docs/examples/csharp/SQLInsertExample.cs
+++ b/docs/examples/csharp/SQLInsertExample.cs
@@ -23,6 +23,7 @@ namespace TDengineExample
             CheckRes(conn, res, "failed to insert data");
             int affectedRows = TDengine.AffectRows(res);
             Console.WriteLine("affectedRows " + affectedRows);
+            TDengine.FreeResult(res);
             ExitProgram(conn, 0);
         }