可以一步步剪切粘贴，但是上百个，麻烦也容易出错。怎样方便解决？谢谢了！

The following assumption is based on the following three assumptions:
1. No gaps in the time series : jan1996 to dec2012, total 204 months
2. The time series are arranged in a sequential order: jan 1996, feb1996, mar1996 ... in your original data file (assume file name: mydata.dta)
3. You have installed the user-written command "renvars" (type "findit renvars" in Stata, then follow instructions)

clear
set obs 204
gen id=_n
egen month=seq(),t(12)
egen year=seq(),b(12)
replace year=year+1995
gen ym=ym(year,month)
format ym %tmMonCCYY
drop month year
save tempdate, replace

use mydata, clear
renvars  jan1996- dec2012/ value1-value204
reshape long value, i(code) j(id)
order  id country code               //optional step
sort id country                        //optional step
merge m:1 id using tempdate,keep(match) nogen

谢谢。

不好意思再问一下，如果我的code也有重复的，does not uniquely identify the observations;该怎么修改呢？我用code 和country 生成一个新的变量d=code+country，应该可以用这个变量uniquely identify the observations了吧。我这样做是不是好的处理方式呢？请你指正。谢谢！

you can change the second part of my above syntax like this:

use mydata, clear
renvars  jan1996- dec2012/ value1-value204
egen group=group(code country)
reshape long value, i(group) j(id)
merge m:1 id using tempdate,keep(match) nogen