Reference in SQL Expression to a group key

Question

Hello to everybody, i am working with a report in Crystal Report 11 and i need some help.
In the design of my report i have two groups corresponding to a table which has two keys. The first one belongs to an Id and the second to a datetime.
The fact is that i have to filter second group with a specific date that i have to obtain with a sql query. So i was thinking in using SQL Expression but i cant make it the right way because i cant filter in the where condition with the id of the superior group. I dont know how to write the where condition.
If anyone can help me i will be grateful.
Thanks.

Answer 1

Thank you Sastry for responding so quickly.
I think you dont understand me. I have this:
-Group 1: id
         -Grupo 2: datetime
the field datetime i need to filter with a specific date. In order to be clear the SQL Expression i made to filter this datetime is:
(select max(datetime) from Table1)
That maximum datetime i need it be for each id in the Group 1 (so the sql expression is not a single value, its a single value for each id of Group1), but i can't put this in the sql expression:
(select max(datetime) from Table1 where Table1.id = Group1.id)
and then the other problem is how to filter the datetime in group 2 with the value of the SQL Expression
PD: Where is the option add command in crystal report?