how to populate 'y' flag

[thanikondharish]

data ex ;
input id $ visit $ result ;
cards ;
101 visit1 22
101 visit2 45
101 visit3 33
102 visit1 22
102 visit2 45
102 visit3 .
103 visit1 22
103 visit2 .
103 visit3 .
104 visit1 22
104 visit2 .
104 visit3 .
;

if visit2 missing and visit3 also missing the results column then assign 'y' in new variable where visit3 like see below dataset

new_flag	id	visit	result
	101	visit1	22
	101	visit2	45
	101	visit3	33
	102	visit1	22
	102	visit2	45
	102	visit3	.
	103	visit1	22
	103	visit2	.
y	103	visit3	.
	104	visit1	22
	104	visit2	.
y	104	visit3	.

[Astounding]

Hmmmm ...

It looks like a lot of people won't even respond to your questions.  I understand the reasons why, but will respond to this one because the question is a reasonable one where it would be difficult to get the answer just by reading the documentation.  

Try it this way:

data want;

set have;

by id;

if first.id then missing_visit_counter = 0;

if result = . then do;

   if visit in ('visit2', 'visit3') then missing_visit_counter + 1;

   if missing_visit_counter = 2  and visit='visit3' then result='y';

end;

drop missing_visit_counter;

run;