How to convert SAS E dates into readable dates - sql

Question

Hi I'm working in SAS platform and I've a data_set with more then 30 columns. there are two date columns in that data-set. dates in that data set are in format as 1.33E12
This is the little part of my table
I want to create a new data-set with few columns and then I'm exporting it to excel file.
my code is
dataset
othercolumns | date1 | date2
- 1.33E12 2.53E14
proc sql noprint;
create table my_data_set as
select ID, col_1, col_2, date1, date2
from data_set;
quit;
I want my date values in date1 and date2 column in a readable format like 10feb2017 as date9. SAS date format so they can be exported to my excel file. right now with E power dates I'm getting ####### as date1 and date2 columns in excel
I've tried
select ID, col_1, col_2, datepaart(date1), datepart(date2)
Warning: Invalid Argument, getting '.' values in date column
select ID, col_1, col_2, date1 date9., date2 date9.
select ID, col_1, col_2, date1 DATEw., date2 DATEw.
Error: Syntax error
select ID, col_1, col_2, date1 format=DATE9., date2 format=DATE9.
Getting the same E date values in my table
select ID, col_1, col_2, put(date1 , date9. ), put(date2 , date9.)
Error: Date value out of range
How to convert the E date into a readable format into my table so i can export it to excel?
this is my export code
ods excel file ="C:\data.xlsx";
ods excel close;
proc export
data = work.my_data_set
dbms = xlsx
outfile = "C:\data.xlsx"
replace;
quit;

Answer 1

data have;
unix_ts = 253402300799;
put unix_ts= datetime21.;
sas_dt = unix_ts + '01JAN1970:0:0'DT ;
put sas_dt= datetime21.;
run;
proc sql;
create table want as
select
(
case
when unix_ts + '01JAN1970:0:0'DT > '27FEB8000:0:0'DT then unix_ts + '01JAN1970:0:0'DT - 2 * 86400
when unix_ts + '01JAN1970:0:0'DT > '28FEB4000:0:0'DT then unix_ts + '01JAN1970:0:0'DT - 1 * 86400
else unix_ts + '01JAN1970:0:0'DT
end
) as sas_date format=datetime21.
from have;
quit;
Rather than cutting and pasting you should understand what is going on with the case statement and the 01-JAN-1970
253,402,300,799
Unix timestamp, seconds from 01-JAN-1970, representing 31-DEC-9999:23:59:59
Likely sentinel value contained in valid_to that OP imprecisely shows as
2.534E14
Date columns presumed to be Unix time stamps.
253,717,747,199
SAS datetime value '31-DEC-9999:23:59:59'DT is seconds from 01-JAN-1960
Timestamp conversion
Unix timestamp values are epoch 01-JAN-1970:0:0:0
SAS datetime values are epoch 01-JAN-1960:0:0:0
So one would presume a SAS values are 10 years (in seconds) greater than Unix value.
The simple approach is to add the epoch base differential to the Unix timestamp to achieve the SAS datetime
SAS_DT = UNIX_TS + '01JAN1970'DT; *Naive conversion;
However, this is incorrect because Unix and SAS calendaring disagree on some leap years!
253,402,300,799 is 31-DEC-9999:23:59:59 per https://www.epochconverter.com/
253,717,747,199 is '31-DEC-9999:23:59:59'DT
difference, 315,446,400 should be SAS '01-JAN-1970:0:0'DT. But the difference is actually '30DEC1969:00:00'DT.
So, adding the epoch baseline differential to a far off Unix timestamp will result in a SAS datetime that does not represent the same calendar point as in Unix.
In other words 253,402,300,799 + '01-JAN-1970:0:0'DT is '02-JAN-10000:0:0'DT -- two days beyond the expected Unix sentinel
Or, after about 8,000 years, the calendar accounting systems in Unix and SAS will deviate by 2 days.
Calendaring deviation
Unix calendaring considers year 4000 to be a leap year, 29-FEB-4000 is valid.
SAS calendaring incorrectly considers 4000 to be a non-leap year, '29-FEB-4000'DT is invalid.
ly4000 = '29-FEB-4000:0:0'DT;
-------------------
77
ERROR: Invalid date/time/datetime constant '29-FEB-4000:0:0'DT.
ERROR 77-185: Invalid number conversion on '29-FEB-4000:0:0'DT.
The same deviation happens again in year 8,000.
The least damaged conversion of Unix timestamp to SAS datetime takes the naïve conversion and subtracts one day for each misaligned leap-day determination in the time frame.

Answer 2

It looks as though you have two different types of UNIX timestamps, which count the number of milliseconds or microseconds from a particular date and time - usually 1st January 1970 00:00:00.000000. Without knowing exactly what sort of timestamps they are, I can only make an educated guess as to how to convert them to human-readable dates. Here are a few possible interpretations:
data example;
date1=2.53e14;
date2=1.33e12;
run;
proc sql;
create table want as
select
intnx('year',datepart(date/1e3),10,'s') format = yymmdd10. as date1a,
intnx('year',datepart(date/1e6),10,'s') format = yymmdd10. as date1b,
intnx('year',datepart(date2/1e3),10,'s') format = yymmdd10. as date2a,
intnx('year',datepart(date2/1e6),10,'s') format = yymmdd10. as date2b
from example;
quit;
The logic here is:
Divide by 1000 or 1000000 to convert to seconds
Interpret the result as a SAS datetime value counting the number of seconds from 1st January 1960 00:00:00
Extract the date component from the datetime
Add 10 years to convert to the UNIX epoch
Hopefully one of these looks right to you.