diff --git a/docs/uniCloud/cf-database.md b/docs/uniCloud/cf-database.md
index 1f0dc2b98ab302f66f1e985cc841438929424bca..6b54e450cc133c026fedf9ca87c43d6b402ef05a 100644
--- a/docs/uniCloud/cf-database.md
+++ b/docs/uniCloud/cf-database.md
@@ -588,6 +588,12 @@ const dbCmd = db.command
 let res = await collection.where({
   a: dbCmd.gt(2)
 }).remove()
+
+// 清理全部数据
+const dbCmd = db.command
+let res = await collection.where({
+  _id: dbCmd.exists(true)
+}).remove()
 ```
 
 ## 更新文档