Oracle analog of MySQL GROUP_CONCAT function

I was looking for Oracle analog of MySQL GROUP_CONCAT function. There is a solution on Ask Tom site. So here it is:

create or replace type string_agg_type as object (

  total varchar2(4000),

  static function ODCIAggregateInitialize(sctx IN OUT string_agg_type )

  return number,

  member function ODCIAggregateIterate(self IN OUT string_agg_type, value IN varchar2 )

  return number,

  member function ODCIAggregateTerminate(self IN string_agg_type, returnValue OUT varchar2, flags IN number)

  return number,

  member function ODCIAggregateMerge(self IN OUT string_agg_type, ctx2 IN string_agg_type)

  return number

);

/

create or replace type body string_agg_type is

  static function ODCIAggregateInitialize(sctx IN OUT string_agg_type)

  return number

  is

  begin

    sctx := string_agg_type( null );

    return ODCIConst.Success;

  end;

  member function ODCIAggregateIterate(self IN OUT string_agg_type, value IN varchar2 )

  return number

  is

  begin

    self.total := self.total || ',' || value;

    return ODCIConst.Success;

  end;

  member function ODCIAggregateTerminate(self IN string_agg_type, returnValue OUT varchar2, flags IN number)

  return number

  is

  begin

    returnValue := ltrim(self.total,',');

    return ODCIConst.Success;

  end;

  member function ODCIAggregateMerge(self IN OUT string_agg_type, ctx2 IN string_agg_type)

  return number

  is

  begin

    self.total := self.total || ctx2.total;

    return ODCIConst.Success;

  end;

end;

/

create or replace function stragg(input varchar2)

return varchar2

parallel_enable aggregate using string_agg_type;

/

After this you can use this function like this:

select t1.id, stragg(t2.name) as names from table1 t1, table2 t2 where t1.id=t2.id group by t1.id;

It will produce comma separated list of the names - something like this:

ID NAMES

-- ------------------------------------

10 CLARK,KING,MILLER

20 SMITH,FORD,ADAMS,SCOTT,JONES

30 ALLEN,BLAKE,MARTIN,TURNER,JAMES,WARD