专家回复了， 不支持。只有用CDS table function。原因也很简单，要支持所有的DB platform。
CDS 里有CAST的关键字，但是专家confirm了不能走类型这条路，因为无法保证这个类型转换在所有DB platform上都工作。
我2013年12月曾经研究过AMDP，这条路可以走通。只是当时没试过如何在CDS view里consume这个生成的procedure。
我现在正在试。
大方向是这样的哈，CDS可以很容易的调用Table function（跟调用CDSview一样），然后table function具体的实现是通过AMDP实现的。
比如下面这个。
define table function ZI_DSO_TF with parameters @Environment.systemField: #CLIENT p_client : abap.clnt, p_rblsrollingaveragemonths : abap.int1, p_revnrollingaveragemonths : abap.int1, p_todaydate : abap.char( 8 ), p_displaycurrency : abap.char( 5 ), p_exchangeratetype : abap.char( 4 ) returns { Client : abap.clnt; CompanyCode : abap.char( 4 ); Customer : abap.char( 10 ); CalendarYear : abap.numc( 4 ) ; CalendarMonth : abap.numc( 2 ); CompanyCodeCurrency : abap.cuky( 5 ); FinancialAccountType : abap.char( 1 ); ExchangeRateType : abap.char( 4 ); CustomerCountry : abap.char( 3 ); CustomerRegion : abap.char( 3 ); AccountingClerk : abap.char( 2 ); CustomerBasicAuthorizationGrp : abap.char( 4 ); DurationUnit : abap.unit( 3 ); ChartofAccounts : abap.char( 4 ); ReconciliationAccount : abap.char( 10 ); DisplayCurrency : abap.cuky( 5 ); DebitAmtInDisplayCrcy : abap.curr( 23, 2 ); CalendarYearMonth : abap.char( 6 ); } implemented by method ZCL_MM_DSO_TF=>tf_test2; Implementation of table function: CLASS ZCL_MM_DSO_TF DEFINITION PUBLIC FINAL CREATE PUBLIC . PUBLIC SECTION. INTERFACES if_amdp_marker_hdb. CLASS-METHODS tf_test2 FOR TABLE FUNCTION ZI_DSO_TF. PROTECTED SECTION. PRIVATE SECTION. ENDCLASS. CLASS ZCL_MM_DSO_TF IMPLEMENTATION. METHOD tf_test2 BY DATABASE FUNCTION FOR HDB LANGUAGE SQLSCRIPT OPTIONS READ-ONLY USING P_DSO12 icustomerfis paddressfis ifidebtorfidata ificompanycode . return select "P_DSO12"."MANDT" AS "CLIENT", "P_DSO12"."COMPANYCODE", "P_DSO12"."CUSTOMER", "P_DSO12"."CALENDARYEAR", "P_DSO12"."CALENDARMONTH", "P_DSO12"."COMPANYCODECURRENCY", "P_DSO12"."FINANCIALACCOUNTTYPE", ( :p_exchangeratetype ) AS "EXCHANGERATETYPE", "=A1"."COUNTRY" AS "CUSTOMERCOUNTRY", "=A1"."REGION" AS "CUSTOMERREGION", "=A2"."ACCOUNTINGCLERK" AS "ACCOUNTINGCLERK", "=A2"."AUTHORIZATIONGROUP" AS "CUSTOMERBASICAUTHORIZATIONGRP", "P_DSO12"."DURATIONUNIT", "=A3"."CHARTOFACCOUNTS" AS "CHARTOFACCOUNTS", "=A2"."RECONCILIATIONACCOUNT" AS "RECONCILIATIONACCOUNT", ( :p_displaycurrency ) AS "DISPLAYCURRENCY", convert_currency( "AMOUNT" => "P_DSO12"."DEBITAMOUNTINCOMPANYCODECRCY", "SOURCE_UNIT" => "P_DSO12"."COMPANYCODECURRENCY", "TARGET_UNIT" => :p_displaycurrency, "REFERENCE_DATE" => "P_DSO12"."ROLLINGAVERAGEMONTHENDDATEDATS", "CONVERSION_TYPE" => :p_exchangeratetype, "CLIENT" => :p_client, "ERROR_HANDLING" => N'FAIL_ON_ERROR', "SCHEMA" => ::CURRENT_OBJECT_SCHEMA, "ACCURACY" => N'highest', "LOOKUP" => N'regular', "OPTIONS" => N'ALLOW_PRECISION_LOSS', "STEPS" => 'convert,shift_back,shift,round' ) as "DEBITAMTINDISPLAYCRCY", "P_DSO12"."CALENDARYEARMONTH" as "CALENDARYEARMONTH" FROM ( ( ( "P_DSO12"( :P_RBLSROLLINGAVERAGEMONTHS, :p_revnrollingaveragemonths, :p_todaydate ) "P_DSO12" LEFT OUTER JOIN "ICUSTOMERFIS" "=A0" ON ( "P_DSO12"."MANDT" = "=A0"."MANDT" AND "=A0"."CUSTOMER" = "P_DSO12"."CUSTOMER" ) ) LEFT OUTER many TO one JOIN "PADDRESSFIS" "=A1" ON ( "P_DSO12"."MANDT" = "=A1"."MANDT" AND "=A0"."ADDRESSID" = "=A1"."ADDRESSID" ) ) LEFT OUTER many TO one JOIN "IFIDEBTORFIDATA" "=A2" ON ( "=A2"."COMPANYCODE" = "P_DSO12"."COMPANYCODE" AND "=A2"."CUSTOMER" = "P_DSO12"."CUSTOMER" AND "P_DSO12"."MANDT" = "=A2"."MANDT" ) ) LEFT OUTER many TO one JOIN "IFICOMPANYCODE" "=A3" ON ( "P_DSO12"."MANDT" = "=A3"."MANDT" AND "=A3"."COMPANYCODE" = "P_DSO12"."COMPANYCODE" ) WHERE NOT ( "P_DSO12"."CALENDARYEARMONTH" IS NULL ) AND NOT ( "P_DSO12"."CALENDARYEARMONTH" IS NULL ) ; ENDMETHOD. ENDCLASS.
我自己做了一个，已经跑通了。