How filter independent of selections

[#1]

Hello everybody.

I need help with that.

I have two selectors client and year

client  year   month

client1 2012  ene

client1 2012 feb

client1 2012 mar

client2 2012 ene

If a select a client1 and year 2012 i have rows for that client in ene,feb,mar

but i select a client2 i have rows only for ene

I need show in a text box the min month and the max month independent of which client i selected.

If i select client1 show ene/mar and the same action with client2

How i write a expression that retrieve the min of mont based on the year selected independent of the client.

Thanks in advance.

[#2 · Accepted solution]

Min({$<client=>}month) should return min month irregardless of client.