Difference in date when one date column has NA

[StarMan]

I am trying to compute the difference in dates based on the date values in two columns and store the results in a third column. The dataset I have looks like this below.

  Id      Col1_Date          Col2_Date
  1       2009-09-10         1916-02-29
  1       2009-09-10         NA

The expected output should be

  Id      Col1_Date          Col2_Date      Date_Diff
  1       2009-09-10         1916-02-29     93.6
  1       2009-09-10         NA             NA

I have tried a simple DataSet as shown below, but this is not working. I am not seeing any values in Date_Diff column.

  DATA  WORK.DF1 ;
  SET   WORK.DF1 ;
  FORMAT DOB date10.;
  Date_Diff = Col1_Date - Col2.Date;
  RUN;

Any help or suggestions on achieving this is much appreciated.

[Reeza]

Are the dates SAS dates, ie numeric with a format such as yymmdd or are they character variables?

If they're character you first have to convert them to a number/numeric to do calculations.

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@StarMan wrote:

I am trying to compute the difference in dates based on the date values in two columns and store the results in a third column. The dataset I have looks like this below.

  Id      Col1_Date          Col2_Date
  1       2009-09-10         1916-02-29
  1       2009-09-10         NA

The expected output should be

  Id      Col1_Date          Col2_Date      Date_Diff
  1       2009-09-10         1916-02-29     93.6
  1       2009-09-10         NA             NA

I have tried a simple DataSet as shown below, but this is not working. I am not seeing any values in Date_Diff column.

  DATA  WORK.DF1 ;
  SET   WORK.DF1 ;
  FORMAT DOB date10.;
  Date_Diff = Col1_Date - Col2.Date;
  RUN;

Any help or suggestions on achieving this is much appreciated.

---

[PaigeMiller]

Great ... but you haven't told us what you do see so we can compare it to the expected output. We need that.

As a potential source of problems, your syntax is wrong here:

Date_Diff = Col1_Date - Col2.Date;

It should say

Date_Diff = Col1_Date - Col2_Date;