Not Enrolled more than once

[hellind]

I have a dataset with Account Number that can be enrolled in a program. The data-set is monthly data. If it is enrolled the Enrolled_Flag = 1 else it is 0.

An account can only be enrolled at most once. How would I detect data issues with the file?

Account AAAA is okay, enrolled in second month.

Account_Number, Year_Month, Enrolled_Flag

AAAA, 202101, 0

AAAA, 202102,1

AAAA, 202103,1

Account BBBB is okay, enrolled and derollled in 4th month

Account_Number, Year_Month, Enrolled_Flag

1

1

1

0

Account CCC is okay always enrolled

1

1

1

1

Account DDDD is NOT okay, enrolled in 2nd month and then then enrolled in 4th month.

0

1

0

1

1

[s_lassen]

Something like this, I think:

data want;
  set have;
  by account enrolled notsorted;
  if first.account then
    n=enrolled;
  else if first.enrolled then
    n+enrolled;
  if last.account;
  if n>1 then
    flag='ERROR';
  else 
    flag=' ';
  keep account flag;
run;