From 9f40b83e967a9d15f2b389cb49ab583ef95a9c22 Mon Sep 17 00:00:00 2001
From: yikeke <yikeke@pingcap.com>
Date: Tue, 23 Jun 2020 15:49:48 +0800
Subject: [PATCH] Update user-defined-variables.md

---
 user-defined-variables.md | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/user-defined-variables.md b/user-defined-variables.md
index 37abb5c70a6d6..47d3cf742e319 100644
--- a/user-defined-variables.md
+++ b/user-defined-variables.md
@@ -7,6 +7,10 @@ aliases: ['/docs/dev/reference/sql/language-structure/user-defined-variables/']
 
 # User-Defined Variables
 
+> **Warning:**
+>
+> User-defined variables are still an experimental feature. It is **NOT** recommended that you use them in the production environment.
+
 The format of the user-defined variables is `@var_name`. `@var_name` consists of alphanumeric characters, `_`, and `$`. The user-defined variables are case-insensitive.
 
 The user-defined variables are session specific, which means a user variable defined by one client cannot be seen or used by other clients.