add content for openSAP course week1 unit4

packages/bookshop/db/schema.cds

@@ -1,35 +1,30 @@
 namespace sap.capire.bookshop;
-using { Currency, managed, cuid } from '@sap/cds/common';
+using { Currency, managed } 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);
+  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;
+  key ID   : Integer;
+  name     : String(111);
+  books    : Association to many Books on books.author = $self;
 }
 
-entity Orders : cuid, managed {
+entity Orders : managed {
+  key ID   : UUID;
   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);
 }
+entity OrderItems {
+  key ID   : UUID;
+  parent   : Association to Orders;
+  book     : Association to Books;
+  amount   : Integer;
+}