How to get more details from a group by query.

How to get more details from a group by query.

consider two tables like:

Object     id_Object  number,
               code          varchar2(10)

RevObj     id_RevObj     number,
                 id_Object      number,
                 code              varchar2(10),
                 RevDate         date

linked with a foreign key in the column id_Object

I need to select for each object the last revision, and with the date I need to obtain also all the data archived in the selected record included the id_RevObj and the code

if I try with a query like this:

select a.id_Object,a.code,max(b.RevDate) RevDate from Object a, RevObj b
where a.id_Object=b.id_Object
group by a.id_Object,a.code

but to get the other details of RevObj I need to add an other level of joint with the table

I thought to order the results by RevDate (desc) and add the where condition rownum=1, but this tecnique doesn't work because the query engine sorts the records only after the results of the where filter.

I curretly use Oracle 7.3.4

Anybody knows an other tecnique more simple ad direct? Thanks in advance,

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Raffaele D'Alba