Merge if

[Mateo Acosta]

Hello,

Hi, I want to use merge, but the problem is that my using data set is an already appended data set, so it has a few duplicates in my identification variable called ident.
Nevertheless, I only need to merge a subgroup of my using data set, for which gen==1, and there are no duplicates for ident in this subgroup.

Is there a way then to only merge to my master data the observations of my using data for which gen==1 ? (other than to first use

 keep if gen==1

on my using data, as I would like to keep it as it is for a moment, I could also use a copy of it, but I was wondering if there was a cleaner way to do this)

Thanks a lot for your help !

[Rich Goldstein]

why not just generate a new variable in your master data set that is called "gen" and is always equal to 1 and then merge on both the id and the gen variable?