rebuild sample to self cont

multitenancy/srv/admin-service.js

@@ -0,0 +1,12 @@
+const cds = require('@sap/cds')
+
+module.exports = cds.service.impl (function(){
+  this.before ('NEW','Authors', genid)
+  this.before ('NEW','Books', genid)
+})
+
+/** Generate primary keys for target entity in request */
+async function genid (req) {
+  const {ID} = await cds.tx(req).run (SELECT.one.from(req.target).columns('max(ID) as ID'))
+  req.data.ID = ID - ID % 100 + 100 + 1
+}