func CheckMKB
lpara tnAgep, tcUsl, tnAgeUsl
local llRet
tcUsl = alltrim(tcUsl)
do case
   case tcUsl == '>'
      llRet = (tnAgep > tnAgeUsl)
   case tcUsl == '<='
      llRet = (tnAgep <= tnAgeUsl)
   otherwise
      MessageBox('Неизвестное условие ' + tcUsl)
      llRet = .NULL.
endcase
return llRet

select p.что_нибудь,u.что_нибудь
 ,icase(h.compr=='>',p.age>h.age
       ,h.compr=='<=',p.age<=h.age
       ,.null.) as CheckMKB
from pacient p 
join usl u on p.spolis=u.spolis and p.npolis=u.npolis
left join hediag h on u.ds==chrtran(h.code,'.','')

select p.что_нибудь,u.что_нибудь
 ,cast(icase(h.compr=='>',p.age>h.age
       ,h.compr=='<=',p.age<=h.age
       ,.null.) as logical) as CheckMKB
from pacient p 
join usl u on p.spolis=u.spolis and p.npolis=u.npolis
left join hediag h on u.ds==chrtran(h.code,'.','')

? '> ' == '>'

create cursor hediag (code c(5), Diag c(10), Age n(3))
insert into hediag ('Z000', 'Общий', 14)
insert into hediag ('Z001', 'Текущий', 19)