Date format in Stata mismatch error

Question

Here is the format of the original date : 01/31/2016 (MDY)

I want to change the format of this date

gen date = date(Date, "MDY")  //Date is the varname of my original date

format date %td

Error : type mismatch r(109)

Answer 1

This works for me

clear
set obs 1 
gen Date = "01/31/2016"
gen date = date(Date, "MDY")  //Date is the varname of my original date
format date %td
list 

     +------------------------+
     |       Date        date |
     |------------------------|
  1. | 01/31/2016   31jan2016 |
     +------------------------+

so I guess you're doing something different and not telling us about it.

That is,

1. The result of date() if it executes without error can only be a numeric variable containing integers.

2. So it will take a daily date format without complaint.

Your error message implies that date is string.

If you really tried to format Date %td, then that could be the error.

Alternatively, if Date is a numeric variable with display format %tdN/D/Y so that a numeric date meaning 31 January 2016 would display as 01/31/16 then to change its format you need not and cannot it push it through date(): you just change the format with format Date %td.

You seem close to the fallacy that display format means storage type. See this paper for a refutation of that idea.