There's a little program that's shown up more than once now in my housekeeping do-files, so it may be useful enough for a blog post, but it doesn't quite warrant a spot in c(sysdir_personal) as a stand-alone ado-file. Here:

// turn this date to Stata format
// if it's not that way already
capture prog drop setStataDate
program setStataDate

args v fmt // fmt can be MDY or YMD

tempname x
capture confirm string variable `v'
if _rc==0 {
   local l`v' : variable label `v'
   gen `x'=date(`v',"`fmt'")
   format `x' %td
   drop `v'
   rename `x' `v'
   label variable `v' "`l`v''"
   // order `v'


I use it with data sets derived from merging other data sets. It's useful if in the original data sets there are string dates in mixed formats -- maybe YYYY-MM-DD in the "master", and MM/DD/YYYY in the "using" -- or if these string dates have labels I want to keep. So, you see why it's not clear that this is worth an ado-file. I don't want to type all the code between the curlies more than once, but usually I don't have to.

I do want to be able to call this program by name, as in setStataDate somedate MDY from within another program, then forget about it, safe in the knowledge that it won't make any difference if somedate is already in Stata format. That's the job of the if-condition you see there, and this is all this little program does.

As to the reason for using the temporary name x, see the comment thread. Temporary names for variables generated only to be renamed are the safe option. The alternative is to use a one-letter convenience name, like x, and I did that first. But what if you want to use this program with a data set that includes a variable named x already?