From aa06e58cb8f1092dda8a1b3c3e526f4b3932cd24 Mon Sep 17 00:00:00 2001
From: cooper-lzy <78672629+cooper-lzy@users.noreply.github.com>
Date: Wed, 23 Aug 2023 17:27:56 +0800
Subject: [PATCH] Update 4.schema.md

---
 .../6.functions-and-expressions/4.schema.md   | 26 +++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/docs-2.0/3.ngql-guide/6.functions-and-expressions/4.schema.md b/docs-2.0/3.ngql-guide/6.functions-and-expressions/4.schema.md
index e6dd6f69523..333d6deb57b 100644
--- a/docs-2.0/3.ngql-guide/6.functions-and-expressions/4.schema.md
+++ b/docs-2.0/3.ngql-guide/6.functions-and-expressions/4.schema.md
@@ -318,6 +318,32 @@ nebula> MATCH (v:player{name:"Tim Duncan"})-[e]->() \
 +----------+
 ```
 
+### typeid()
+
+typeid() returns the internal ID value of the Edge type of the edge, which can be used to determine the direction by positive or negative.
+
+Syntax: `typeid(<edge>)`
+
+- Result type: Int
+
+Example:
+
+```ngql
+nebula> MATCH (v:player)-[e:follow]-(v2) RETURN e,typeid(e), \
+        CASE WHEN typeid(e) > 0 \
+        THEN "Forward" ELSE "Reverse" END AS direction \
+        LIMIT 5;
++----------------------------------------------------+-----------+-----------+
+| e                                                  | typeid(e) | direction |
++----------------------------------------------------+-----------+-----------+
+| [:follow "player127"->"player114" @0 {degree: 90}] | 5         | "Forward" |
+| [:follow "player127"->"player148" @0 {degree: 70}] | 5         | "Forward" |
+| [:follow "player148"->"player127" @0 {degree: 80}] | -5        | "Reverse" |
+| [:follow "player147"->"player136" @0 {degree: 90}] | 5         | "Forward" |
+| [:follow "player136"->"player147" @0 {degree: 90}] | -5        | "Reverse" |
++----------------------------------------------------+-----------+-----------+
+```
+
 ### src()
 
 src() returns the source vertex ID of an edge.