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。
http://scn.sap.com/community/abap/blog/2013/12/10/an-example-of-amdp-abap-managed-database-procedure-in-740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。