I have three tables (joined) with a number of conditions and would also like to have a contition on maximum value for three different tables

Code:
Select XX.x, YY.y, ZZ.z, WW.w
from XX 
Join YY on XX.x = YY.y
Join ZZ on YY.ya = ZZ.z And XX.x = ZZ.zb
Join WW on WW.w = ZZ.zc
where x = 'my_id'
--- How can I and do this??? 
---- max (XX.x_date, YY.y_date, ZZ.c_date) dat
and dat < somedate
...