9i下：
create type strcat_type as object (
cat_string varchar2(4000),
static function ODCIAggregateInitialize(cs_ctx In Out strcat_type) return number,
member function ODCIAggregateIterate(self In Out strcat_type,value in varchar2) return number,
member function ODCIAggregateMerge(self In Out strcat_type,ctx2 In Out strcat_type) return number,
member function ODCIAggregateTerminate(self In Out strcat_type,returnValue Out varchar2,flags in number) return number
)
/
create type body strcat_type is
static function ODCIAggregateInitialize(cs_ctx IN OUT strcat_type) return number
is
begin
cs_ctx := strcat_type( null );
return ODCIConst.Success;
end;
member function ODCIAggregateIterate(self IN OUT strcat_type,
value IN varchar2 )
return number
is
begin
self.cat_string := self.cat_string || ','|| value;
return ODCIConst.Success;
end;
member function ODCIAggregateTerminate(self IN Out strcat_type,
returnValue OUT varchar2,
flags IN number)
return number
is
begin
returnValue := ltrim(rtrim(self.cat_string,','),',');
return ODCIConst.Success;
end;
member function ODCIAggregateMerge(self IN OUT strcat_type,
ctx2 IN Out strcat_type)
return number
is
begin
self.cat_string := self.cat_string || ',' || ctx2.cat_string;
return ODCIConst.Success;
end;
end;
/
CREATE or replace
FUNCTION strcat(input varchar2 )
RETURN varchar2
PARALLEL_ENABLE AGGREGATE USING strcat_type;
/
使用方法：
select t2.kdm_mdid_pk,t2.kdm_title,
strcat(t3.subject_mc_content) message
from t_knodoc_rel_subjects t1,
T_KNO_DOC_METADATA t2,
T_SUBJECT_MULTILINGUAL_CONTENT t3
where t1.krs_kdm_mdid_fk=t2.kdm_mdid_pk
and t1.krs_subid_fk=t3.subject_mc_id_pk
group by t2.kdm_mdid_pk,t2.kdm_title
10g下：
select t2.kdm_mdid_pk,t2.kdm_title,WMSYS.WM_CONCAT(t3.subject_mc_content) message
from t_knodoc_rel_subjects t1,
T_KNO_DOC_METADATA t2,
T_SUBJECT_MULTILINGUAL_CONTENT t3
where t1.krs_kdm_mdid_fk=t2.kdm_mdid_pk
and t1.krs_subid_fk=t3.subject_mc_id_pk
group by t2.kdm_mdid_pk,t2.kdm_title