diff --git a/Onderdelen.md b/Onderdelen.md
index 428534d..de87a2f 100644
--- a/Onderdelen.md
+++ b/Onderdelen.md
@@ -13,4 +13,14 @@ graph TD;
     A-->C;
     B-->D;
     C-->D;
+```
+
+```mermaid
+---
+title: Order example
+---
+erDiagram
+    CUSTOMER ||--o{ ORDER : places
+    ORDER ||--|{ LINE-ITEM : contains
+    CUSTOMER }|..|{ DELIVERY-ADDRESS : uses
 ```
\ No newline at end of file