serial ID

[Smitha9]

Hi,

I have repetitive ClassID and I want to give seperated ID per classID. 

ClassID    ID

1               1

1               2

1             3

2              1

2             2

2             3

I want create ID's like above using the classID.

can anyone help me with this?

thank you in advance

[mklangley]

Is this what you're looking for?

data have;
    input ClassID;
    datalines;
    1
    1
    1
    2
    2
    2
    3
    3
    3
    3
    ;
run;

data want;
    set have;
    by ClassID;
    retain ID;
    if first.ClassID then ID = 1;
    else ID = ID + 1;
    output;
run;

Note: I am assuming your input data is sorted by ClassID.