SAS datetime conversion

[DeniseDorland]

I want to add 24 hrs to DTC = 2023-10-16T09:30 so as to get the result as 2023-10-17T09:30. How should I write the SAS code?

[SASKiwi]

Try this:

data Want;
  set Have;
  MyDateTime = MyDateTime + '24:00't;
run;

[DeniseDorland]

getting this error

[Tom]

You cannot add character strings.

You will have to first convert the character string into an actual datetime value.

input(dct_trt_1,anydtdtm20.) + '24:00:00't 

Do you want get a datetime value back?  or do you want another character string?

[DeniseDorland]

Answer: 2023-10-17T09:30

[Tom]

---

@DeniseDorland wrote:
Answer: 2023-10-17T09:30

---

Huh?

Do you want a character string? Or a number?

Do you plan on doing more arithmetic with this new datetime value? If so keep it as a number, otherwise you will have to convert it back from character again.

[Tom]

Since both DATETIME and TIME values are stored in seconds the easiest way is to add 24 hours worth of seconds, or '24:00:00't .

data want;
  set have;
  new_var = old_var + '24:00:00't ;
  format new_var datetime19.;
run;

[DeniseDorland]

still getting the error

[ballardw]

Your DTC_TRT_1 variablef, and therefore like the others, are CHARACTER values. They are character values that will not convert to a "nice" numeric datetime value unless you force such. When you use a character variable in arithmetic SAS will attempt to convert it to a number but has very limited rules when the value is more complex than something like "123". So it is up to you to do several things: 1) convert the string to a datetime value to use in the addition.

If the result is a new numeric  variable then you will want to assign a FORMAT to display the value in a manner that people can recognize.

data example;
   dtc_trt_1 ="2023-10-16T09:30";
   dtc_wsh =    input(dtc_trt_1,e8601dt.) +'24:00't;
   format dtc_wsh e8601dt.;
run;

Note that I create a variable that is character as your LOG states for dtc_trt_1. Then use the INPUT function with an appropriate INFORMAT to create a datetime numeric value then add the time literal 24 hours. The shortest default format SAS has supplied that matches your appearance will have 19 characters so will display seconds as :00. If that is objectionable then it is possible to create a custom format that does otherwise.

https://communities.sas.com/t5/SAS-Communities-Library/Working-with-Dates-and-Times-in-SAS-Tutorial/... has a PDF with much information about dates, times and datetime values.

Please do yourself an us a favor and copy the text from log and on the forum open a text box using the </> icon above the message window and paste the text. That way we can copy/paste/edit your text. If we have to retype considerable amounts of text to answer questions you may not get as good or complete an answer.

[Tom]

If you just want to make another string it might be easier to just convert the beginning of your string to a DATE value and then subtract one before converting it back into a string.

dtc_wsh = put(input(dtc_trt_1,yymmdd10.)-1,yymmdd10.)||substr(ctc_trt_1,11,5);

Or perhaps simpler to copy the string first (then you get a variable with the same length as the original) and then replace the first 10 characters with the new date.

dtc_wsh = dtc_trt_1;
substr(dtc_wsh,1,10) =put(input(dtc_trt_1,yymmdd10.)-1,yymmdd10.);

[SASKiwi]

@DeniseDorland - I'm curious to know why your datetime is stored in a character variable - is that by design or just the way it was imported into SAS? As you can see, doing calculations on a character datetime is a whole lot harder than if it was a SAS datatime which is stored in a numeric variable.