st: Adding variables to datasets

[mmolina@uniroma3.it]

Dear Statalist,

I'd need to combine three datasets.

For the first two, I do:

use filename

append using filename

and it's fine. Now I'd like to add only one variable from a third dataset.
This variables matches with id from the previous two (it is a new variable
about observation id from a previous year).

I tried again with 'append using filename' but it generates too many
missing values.

Could you please help me?

Thanks,

Maria

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