create or replace type list_agg as object( total varchar2(4000), static function ODCIAggregateInitialize(sctx IN OUT list_agg) return number, member function ODCIAggregateIterate(self IN OUT list_agg, value IN varchar2) return number, member function ODCIAggregateTerminate(self IN list_agg, returnValue OUT varchar2, flags IN number) return number, member function ODCIAggregateMerge(self IN OUT list_agg, ctx2 IN list_agg) return number);create or replace type body list_agg is static function ODCIAggregateInitialize(sctx IN OUT list_agg) return number is begin sctx := list_agg(null); return ODCIConst.Success; end; member function ODCIAggregateIterate(self IN OUT list_agg, value IN varchar2) return number is begin self.total := self.total || value; return ODCIConst.Success; end; member function ODCIAggregateTerminate(self IN list_agg, returnValue OUT varchar2, flags IN number) return number is begin returnValue := substr(self.total, 2); return ODCIConst.Success; end; member function ODCIAggregateMerge(self IN OUT list_agg, ctx2 IN list_agg) return number is begin self.total := self.total || ctx2.total; return ODCIConst.Success; end;end;CREATE OR REPLACE FUNCTION ColumnToRow(input varchar2 )RETURN varchar2PARALLEL_ENABLE AGGREGATE USING list_agg;select ColumnToRow(','||Tname) from tab where rownum<10;