st: how to drop repeated observations?

[Isabelle.Roux@ehess.fr]

Hello,

I'm new in using Stata and I have a dataset with french
firms'immatriculation numbers (this variable is called siren). I would
like to drop observations when the same siren appears for the second, the
third...time, but I don't achieve to do that.
Thank you very much for your help.

Yours sincerly,

Isabelle Roux


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