Compare variable in two stata files and list

[Yehani Wedatilake]

I have two datasets and I want to make sure that the same IDnumber has not been recorded twice in the two different data sets (They are two different stata files). See example below. Variable name is IDnumber. How can I ask stata to highlight where the same IDnumber has been recorded twice. for example in this data set, IDnumber 1 and 3 have been recorded twice and I would like stata to list these for me.
Eg.
Dataset1
IDnumber
1
2
3
4
5

Dataset2
IDnumber
1
3
6
7
8

Thanks very much

[Carlo Lazzaro]

Yehani:
welcome to this forum.
I would -append- the two files first.
Then I would type:

sort id

and eventually I would call:

duplicates list id

[Rich Goldstein]

an alternative: merge the two data sets; the value of the automatically generated _merge variable will tell you whether an id is in both file or, if only one file, which file it is from; see

help merge

[Yehani Wedatilake]

an alternative: merge the two data sets; the value of the automatically generated _merge variable will tell you whether an id is in both file or, if only one file, which file it is from; see

help merge

Thanks this works too

[Yehani Wedatilake]

Yehani:
welcome to this forum.
I would -append- the two files first.
Then I would type:

sort id

and eventually I would call:

duplicates list id

Thank you for this. It works !