close databases all

create cursor tt (id i, idGroup i, fam c( 10 ))

insert into tt values ( 5 , 3 ,'Петров')
insert into tt values ( 6 , 3 ,'Петров')
insert into tt values ( 7 , 3 ,'Петров')
insert into tt values ( 8 , 3 ,'Петров')
insert into tt values ( 1 , 4 ,'Иванов') 
insert into tt values ( 2 , 4 ,'Иванов')
insert into tt values ( 3 , 2 ,'Смирнов')
insert into tt values ( 4 , 2 ,'Смирнов')

select tt.id,tt.fam,idGroup,  0  as Count ;
from tt  ;
order by tt.idGroup ;
into cursor pp readwrite

local lnidGroup,lnCounter
lnidGroup =  0 
lnCounter =  0 
update pp set Count=idtt(pp.idGroup,@lnidGroup,@lnCounter)

select pp
brow

return 


function idtt(tnId,tnOldId,tnCounter)
	*set step on 
	tnCounter = iif(tnId<>tnOldId, 1 ,tnCounter+ 1 )
	tnOldId   = iif(tnId<>tnOldId,tnId,tnOldId)
	return tnCounter
endif

if object_id('tempdb..#tt') is not null drop table #tt
if object_id('tempdb..#my') is not null drop table #my

create table #tt (id int, idGroup int, fam varchar( 10 ))

insert into #tt values ( 5 , 3 ,'Петров')
insert into #tt values ( 6 , 3 ,'Петров')
insert into #tt values ( 7 , 3 ,'Петров')
insert into #tt values ( 8 , 3 ,'Петров')
insert into #tt values ( 1 , 4 ,'Иванов') 
insert into #tt values ( 2 , 4 ,'Иванов')
insert into #tt values ( 3 , 2 ,'Смирнов')
insert into #tt values ( 4 , 2 ,'Смирнов')

select *, counter= 0 
   into #my
   from #tt
   order by idGroup 

declare @nCounter int, @nOldGroup int
select @nCounter= 0 , @nOldGroup= 0 

update #my set  @nCounter=case when idGroup<>@nOldGroup then  1  else @nCounter+ 1  end, 
		@nOldGroup=idGroup, 
		counter=@nCounter

select * from #my