Verifying that values of two variables don't overlap

[bkq32]

I have a data set with two IDs and variable NLEV to identify ID1 duplicates:

data have;
 input id1$ id2$ nlev;
cards;
1 A 1
1 A 2
2 B 1
2 B 2
3 C 1
3 C 2
3 C 3
3 B 4
;
run;

How can I verify that values for ID2 only correspond to one unique ID1 value. In this example, I'd want SAS to flag records where ID2="B" (or something similar) because ID2="B" corresponds to both ID1=2 and ID1=3.

[novinosrin · Accepted solution]

Hi @bkq32   By any chance, is this what you are after?

data have;
 input id1$ id2$ nlev;
cards;
1 A 1
1 A 2
2 B 1
2 B 2
3 C 1
3 C 2
3 C 3
3 B 4
;
run;

proc sql;
create table want as
select *, count(distinct id1)>1 as flag
from have
group by id2
order by id1,nlev;
quit;

[bkq32]

Yes, that's perfect. Thank you!