select count(ov.hn) as chn
from vn_stat ov, ovst ovst, patient pt
where ov.vn=ovst.vn and pt.hn=ov.hn and ov.vstdate between "2008-01-01" and "2008-02-29"
and ov.age_y>= 0
and ov.age_y<= 200
and ( (ov.pdx = "N189")
or (ov.dx0 = "N189")
or (ov.dx1 = "N189")
or (ov.dx2 = "N189")
or (ov.dx3 = "N189")
or (ov.dx4 = "N189")
or (ov.dx5 = "N189") )