re: Data Selection

[twildone]

Hi...I have a dataset that I want to select only or identify those customers as repaet customers by their ID. I can obtain a partial dataset by using the lag function but the very first record of each customer who is a repeat customer does not have "Yes" as the correct entry. Any suggestions how I might be able include the first time that  repeat customer ID is found...Thanks.

Have:

ID	DATE	SALES
1223	2016-01-23	73.55
1445	2016-01-12	88.45
1445	2016-02-11	54.70
1445	2016-03-10	66.15
1733	2016-02-08	34.50
1649	2016-02-27	66.30
1649	2016-03-13	88.20

Want:

ID	Date	Sales	Repeat
1223	2016-01-23	73.55
1445	2016-01-12	88.45	Yes
1445	2016-02-11	54.70	Yes
1445	2016-03-10	66.15	Yes
1733	2016-02-08	34.50
1649	2016-02-27	66.30	Yes
1649	2016-03-13	88.20	Yes

[Reeza · Accepted solution]

Use the By groups?

data want;
set have;

BY ID;

if not first.ID then repeat='Yes';

run;

EDIT: Sorry, it looks like you want to identify all records that aren't unique. You can do this using First/Last, where not first.ID and last.iD

data want;
set have;

BY ID;

if not (first.ID and last.ID) then repeat='Yes';

run;