Aggregation Functions in CDS Views
  Example 1: @AbapCatalog.sqlViewName:  'ZVB_TEST_VIEW'   @AbapCatalog.compiler.compareFilter:  true   @AbapCatalog.preserveKey:  true   @AccessControl.authorizationCheck:  #CHECK   @EndUserText.label:  'Test cds'   define  view  ZVB_TEST_CDS     as  select  from  ekpo   {     key  ekpo . ebeln       as  PO_Number ,     count(distinct  ekpo . ebelp )  as  Item_count ,         min( ekpo . ebelp )  as  Min_PO_item ,         max( ekpo . ebelp )  as  Max_PO_Item ,         sum ( ekpo . netpr )  as  Price   }   group  by     ekpo . ebeln     Output:     Example 2:   @AbapCatalog.sqlViewName:  'ZVB_TEST_VIEW'   @AbapCatalog.compiler.compareFilter:  true   @AbapCatalog.preserveKey:  true   @AccessControl.authorizationCheck:  #CHECK   @EndUserText.label:  'Test cds'   define  view  ZVB_TEST_CDS     as  select  from  ekko     inner  join  ekpo on  ekko . ebel...