Merging two datasets with a common variable

[Lydia Ewurabena Gamey]

Hello all,
I am using STATA 16
Please I want to merge two datasets, using the common variable medcode, but i cannot seem to troubleshoot it.
I have sorted medcode in both files.
Thanks for the assistance.

Please find datasets below

A.

* Example generated by -dataex-. For more info, type help dataex
clear
input str10 patid str5 pracid int dob str17 medcode long(eventdate gender)
"075G" "a9906" 19734 "12K7.00"  100 1
"08me" "d9868"  8042 "12K7.00" 4504 1
"06zE" "g7683" 18274 "12K7.00" 4545 2
"05dl" "g6638" 18639 "12K7.00" 1204 1
"06d6" "c7781" 13886 "12K7.00" 1061 1
"02k0" "c9877" 17542 "12K7.00" 2530 2
"05eS" "f9882" 17174 "12K7.00" 2345 1
"06oH" "h9876" 20090 "12K7.00" 3640 1
"022e" "f7687" 19725 "12K7.00"  217 2
"05yA" "e6886" 20096 "12K7.00" 5041 1
end
format %tdnn/dd/CCYY dob
label values eventdate eventdate
label def eventdate 100 "  1/7/2015", modify
label def eventdate 217 "  2/6/2017", modify
label def eventdate 1061 "  9/3/2017", modify
label def eventdate 1204 " 10/1/2017", modify
label def eventdate 2345 "14/10/2011", modify
label def eventdate 2530 "15/10/2018", modify
label def eventdate 3640 "22/05/2017", modify
label def eventdate 4504 "27/07/2017", modify
label def eventdate 4545 "27/10/2016", modify
label def eventdate 5041 "30/11/2016", modify
label values gender gender
label def gender 1 "Female", modify
label def gender 2 "Male", modify

B.

* Example generated by -dataex-. For more info, type help dataex
clear
input str17 medcode str60 description
"0....00" "Occupations"                  
"0....11" "Job"                          
"01...00" "Top managers"                  
"01...11" "Administrators - top"          
"011..00" "National gov't. top managers"  
"011Z.00" "Nat. gov't. general admin. NOS"
"012..00" "Local gov't.- top managers"    
"012Z.00" "Local gov't.- top manager NOS"
"013..00" "Top managers - business"      
"013..11" "Business - top men"            
end

[Andrew Musau]

You do not show what command you ran and the resulting output. With "dataset A" open, the command should be something like

merge m:1 medcode using "dataset B"

where you replace "dataset B" with the name of your second dataset.

[Lydia Ewurabena Gamey]

Apologies for leaving that out. I used similar command. Please find the command and result below.

. merge m:1 medcode using read_code.dta (dataset B)
(note: variable medcode was str7, now str17 to accommodate using data's
values)
variable medcode does not uniquely identify observations in the using data

Thanks

[Andrew Musau]

Check why you have duplicates of the variable medcode

use read_code.dta, clear
bys medcode: list if _N>1

If these duplicates are real duplicates and do not contain additional information in terms of other variables, then

duplicates drop medcode, force

before executing the merge.

[Lydia Ewurabena Gamey]

Hi Andrew, worked perfectly !! Thanks a mil