Do loop iteration issue

[greg6363]

I am trying to use a do loop to number each individual issue date by account number in my data set.  Here is my data set:

AccountNumber     IssueDate      IssueNumber

        1001                1/1/2020               

        1001                2/1/2020               

        1001                3/1/2020               

        1001                4/1/2020               

        1002                1/2/2020               

        1002                1/15/2020             

        1003                1/5/2020               

        1003                1/20/2020             

        1003                1/31/2020             

I want to populate the IssueNumber field with the iterative do loop to number each entry for every individual AccountNumber as you see in .  The AccountNumber could have 1, 2, 5, 10, up to 52.

    DATA Records;

    SET Master;
DO i = 1 to 52; /*value range - could be less according to count of issuedate field*/
    DO IssueNumber = 1 to i;
        output;
            END;
    END;
RUN;

This is how I want to see from the output data set. 

AccountNumber     IssueDate      IssueNumber

        1001                1/1/2020               1

        1001                2/1/2020               2

        1001                3/1/2020               3

        1001                4/1/2020               4

        1002                1/2/2020               1

        1002                1/15/2020             2

        1003                1/5/2020               1

        1003                1/20/2020             2

        1003                1/31/2020             3

The code I have provided above is not providing the output I need for analysis.  Any feedback would be greatly appreciated.  Thanks.

[RichardDeVen · Accepted solution]

Use BY group processing and automatic variable FIRST.<byvar> to reset the counter at the start of each group.

Example:

data want;
  set have;
  by AccountNumber;
  if first.AccountNumber
    then IssueNumber = 1; 
    else IssueNumber + 1;  /* sum statement */
run;

[greg6363]

It worked. Thanks so much. Appreciate it.