date time issue

[SAS_inquisitive]

I have a exposure date and start of adverse events date.  I want  to find the last exposure or same day exposure for each adverse event date.

Exposure date data

Subj     exposure_date

A         2015-09-10

A        2015-10-01

A        2015-11-12

A       2015-11-25

Adverse event date data

Subj     adverse_event_date

A          2015-09-23

A          2015-09-23

A          2015-10-16

A          2015-10-16

A         2015-11-05

A         2015-11-05

Desired data set

Subj      Last_exposure_date

A         2015-09-10

A         2015-09-10

A        2015-10-01

A        2015-10-01

A       2015-10-01

A       2015-10-01

[RW9 · Accepted solution]

Hi,

Well, not typing test data in so this is an untested shell:

proc sql;
  select  AE.*,
          (select max(EXPOSURE_DATE) from EX where SUBJ=AE.SUBJ and EXPOSURE_DATE <= AE.ADVERSE EVENT_DATE) as EXPOSURE_DATE
  from    AE AE;
quit;

[SAS_inquisitive]

@RW9 I have one more question. If EX data set has one more variable, how can I add it to resulting data set? I tried to put it as the separate subquery as you did, it is not working.