Update for unit 6

packages/bookshop/db/schema.cds

@@ -1,35 +1,8 @@
 namespace sap.capire.bookshop;
-using { Currency, managed, cuid } from '@sap/cds/common';
 
-entity Books : managed {
-  key ID : Integer;
-  title  : localized String(111);
-  descr  : localized String(1111);
-  author : Association to Authors;
-  stock  : Integer;
-  price  : Decimal(9,2);
-  currency : Currency;
-}
-
-entity Authors : managed {
-  key ID : Integer;
-  name   : String(111);
-  dateOfBirth  : Date;
-  dateOfDeath  : Date;
-  placeOfBirth : String;
-  placeOfDeath : String;
-  books  : Association to many Books on books.author = $self;
-}
-
-entity Orders : cuid, managed {
-  OrderNo  : String @title:'Order Number'; //> readable key
-  Items    : Composition of many OrderItems on Items.parent = $self;
-  total    : Decimal(9,2) @readonly;
-  currency : Currency;
-}
-entity OrderItems : cuid {
-  parent    : Association to Orders;
-  book      : Association to Books;
-  amount    : Integer;
-  netAmount : Decimal(9,2);
+@cds.persistence.exists
+entity Books {
+    key ID: UUID;
+        title  : String(111); 
+        descr  : String(1111);
 }