How can i count the difference between dates within the same column (SAS)

Question

Total beginner stuff in SAS, but still..How can i count the number of dates within the same column for each ID?

Dataset want (I have added the variable Count_date, which i want to create):

ID  datechar   Count_date
1   01-09-2014 1
1   01-09-2014 1
1   01-09-2014 1
1   02-09-2014 2
1   02-09-2014 2
1   02-09-2014 2
1   03-09-2014 3
1   03-09-2014 3
1   03-09-2014 3
2   01-08-2014 1
2   01-08-2014 1
2   01-08-2014 1
2   01-08-2014 1
2   02-08-2014 2
2   02-08-2014 2
2   02-08-2014 2
2   02-08-2014 2
2   04-08-2014 4
2   04-08-2014 4
2   04-08-2014 4
2   04-08-2014 4
3   05-06-2011 1
3   05-06-2011 1
3   05-06-2011 1
3   05-06-2011 1
3   08-06-2011 4
3   08-06-2011 4
3   08-06-2011 4
3   08-06-2011 4

I want to create there variable Count_date. I have tried:

Data want;
    set have;
        by ID;
        retain count_date;
        if first.datechar then count_date = 1;
        else count_date = count_date + 1; 
    run;

What am i doing wrong?

Thanks alot!!

Answer 1

BY and FIRST are not specified correctly.

Data want;
    set have;
        by ID datechar;
        retain count_date;
        if first.ID then count_date = 1;
        else if first.datechar then count_date + 1;
    
run;