>I have a parent and child table.
>
>I have created query in which there are that parent and child table (in relation).
>
>I have made report that contains that query.
>In report I have made group by field (field that is used for relation).
>Now I want to sort details (by date) in every group but I can't do that!
>I have put Order by (date) in query but it doesn't work.
>
>How to sort details?

You mean you're using 2 tables for this? Easy solution would be a single SQL select where dat ais already sorted on groupfield and then by date.
Using a2 tables and relation however you can do it using a compund index on child. ie:
consider parent table id fiedl name is myID (integer) and child relation field name is myParentID and a date field named myDate.

use myChild
index on padl(myParentID,10,'0')+dtoc(myDate,1) && dtos() and optionally descending clause

Your relational expression would be padl(myID,10,'0'). ie:
select myParent
set relation to padl(myParentID,10,'0') into myChild

PS: Prior to VFP9 thiswould also work reversing the child and parent.

Cetin