Dear All, J found this question here (in Chinese). Suppose that I have two datasets. Data A is:
Code:
* Example generated by -dataex-. For more info, type help dataex
clear
input float(id1 id2 sells)
1 11 4
1 11 5
1 11 6
2 22 3
2 22 3
3 33 4
3 33 2
end
and Data B is:
Code:
* Example generated by -dataex-. For more info, type help dataex
clear
input float(id1 id2 costs)
1 11 .2
2  . .3
. 33 .4
end
The desired result is
Code:
* Example generated by -dataex-. For more info, type help dataex
clear
input float(id1 id2 sells costs)
1 11 4 .2
1 11 5 .2
1 11 6 .2
2 22 3 .3
2 22 3 .3
3 33 4 .4
3 33 2 .4
end
The rule is that (1) first merge A with B using id1 (1 and 2), and then (2) the remaining ones are merged using id2 (33). Any suggestions are appreciated.