Multiple If-then conditions

[arde]

I am trying to get this output:

Status	Days	DATE1	DATE2	flag
Unknown	20	9-Sep-18	10-Sep-18	Dates do not match
Unknown	30	.	10-Sep-18	data is missing
	40	10-Sep-18	10-Sep-18	data is missing
Unknown	40	10-Sep-18	10-Sep-18

data have;
length Status $10 Days 8.;
input STATUS $ DATE1 :date9. DATE2 :date9. Days;
format DATE1 date9. DATE2 date9. ;
datalines;
Unknown 09Sep2018 10Sep2018 20
Unknown . 10Sep2018 30
. 10Sep2018 10Sep2018 40
Unknown 10Sep2018 10Sep2018 40
;
run;

data want;
set have;
length flag $ 60;
if DATE1 ne null and DATE2 ne null and DATE1 ne DATE2 then do flag = "Dates do not match"; end;
if (DATE1 =null or Status = null) and (Days > 20) then do flag="data is missing"; end;
run;

The first if statement works, but the second does not.  Any help would be truly appreciated.

[Reeza]

DATE1 =null this may be your issue, is there a note in your log to that effect?

I get one when I try and use NULL.

I think the valid syntax in SAS would be using the MISSING. I recommend missing because it works for numeric and character. Otherwise a numeric missing is denoted with a period and a character missing is with a space.

if not missing(date1)  then ...;

*check how many missing among a list of variables;
if nmiss(date1, date2) eq 0 then ...;

*if numeric variable;
if date1 ne . then ...;

*if characater variable;
if date1 ne '' then ...;

---

@arde wrote:

I am trying to get this output:

Status	Days	DATE1	DATE2	flag
Unknown	20	9-Sep-18	10-Sep-18	Dates do not match
Unknown	30	.	10-Sep-18	data is missing
	40	10-Sep-18	10-Sep-18	data is missing
Unknown	40	10-Sep-18	10-Sep-18

data have;
length Status $10 Days 8.;
input STATUS $ DATE1 :date9. DATE2 :date9. Days;
format DATE1 date9. DATE2 date9. ;
datalines;
Unknown 09Sep2018 10Sep2018 20
Unknown . 10Sep2018 30
. 10Sep2018 10Sep2018 40
Unknown 10Sep2018 10Sep2018 40
;
run;

data want;
set have;
length flag $ 60;
if DATE1 ne null and DATE2 ne null and DATE1 ne DATE2 then do flag = "Dates do not match"; end;
if (DATE1 =null or Status = null) and (Days > 20) then do flag="data is missing"; end;
run;

The first if statement works, but the second does not.  Any help would be truly appreciated.

---

[arde]

thank you

[Astounding · Accepted solution]

The first statement working is a happy accident.  It forces SAS to create a variable named NULL which will be numeric and contain a missing value.  So you accidentally end up checking whether DATE1 contains a missing value, and whether DATE2 contains a missing value.

NULL is not a keyword in a DATA step (which is why your second statement runs into trouble).  Try it this way:

data want;
set have;
length flag $ 60;
if (DATE1 ne .) and (DATE2 ne .) and DATE1 ne DATE2 then flag = "Dates do not match"; 
if (DATE1 = . or Status = " ") and (Days > 20) then flag="data is missing"; 
run;

[arde]

thank you