To test your code there are various ways. Unit test are the most common one, not really a SAS concept though, a programming methodology more so.    *My* method is to run a PROC FREQ on the input variable. I look for all of the different unique cases that are possible and create small dataset with those values only. You can pipe your PROC FREQ output to a data set to help with this. Then you test it on the small data set where you can verify all data points. Once it's verified then you apply it to your big dataset.    You can also run a PROC FREQ on the input variable and compare it to the output but if you have 4million unique values.    proc freq data=want; table inputVariable * outputVariable / out = check; run;     @GN0001 wrote: Hi Reza & all, What I asked was when we apply a function to a data set, for example a scan function on a values of a variable, how can we make sure our function has modified all the values? I usually eyeball it and a little of log can help. Is there any other approach? please advise me. respectfully,  blue blue   ... View more

FYI - your code as posted does generate errors for me - there are three syntax errors in your code. ... View more

This syntax didn't work:  A subquery can not select more than one column... usually a subquery is used incorrectly in an expression   proc sql; select * from have as a where dt=(select MAX(dt) from have as b WHERE a.id=b.id); quit; How can I fix this issue? Regards, Blueblue ... View more

In that code MMDDYY is an INFORMAT and YYMMDD is a FORMAT.  MMDDYY10. is the informat specification you are using with the INPUT() function. Since you set the width at 10 bytes it will only use the first 10 bytes of the character variable STRING.  YYMMDD10. is the format specification you are setting as the default way to display the values of DATE.    So the result is that DATE is a numeric value that has the number of days since start of 1960 and by default it will print as 10 characters with the first four being the YEAR number then a hyphen then two digits for the month number within that year another hyphen and then two digits for the day within that month.   In SAS you use a FORMAT to convert values into text.  You use an INFORMAT to convert text into values. You can use the INPUT statement to read text into values.  You can use the INPUT() function to convert text in a character string into a value. You can use the PUT statement to write values as text.  You can use the PUT() function to convert values into a character string.    You can use the FORMAT statement in a data step to permanently attach a particular format to a variable so that SAS will use that format when displaying the values by default.  Similarly you can use an INFORMAT statement to attach an informat that you want SAS to use by default when reading values into the variable via and INPUT statement.     ... View more

Maxim 4. Try It. Or read the documentation. ... View more

This option tells SAS to only read the BY variables when sorting. The other variables are added as a second step. Pros: Small utility file as few variables are moved around Cons: Fetching the other variables when the sort is complete can take a long time    ... View more

The log should have told you most of the problems: 11 data mbrtest; 12 Input Id EffeDate; 13 format EffeData mmddyyyy10.; ----------- 484 NOTE 484-185: Format MMDDYYYY was not found or could not be loaded. 14 datalines; NOTE: Variable EffeData is uninitialized. NOTE: Invalid data for EffeDate in line 15 3-12. RULE: ----+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8----+-- 15 1 12/11/2021 Id=1 EffeDate=. EffeData=. _ERROR_=1 _N_=1 NOTE: Invalid data for EffeDate in line 16 3-12. 16 1 12/12/2021 Id=1 EffeDate=. EffeData=. _ERROR_=1 _N_=2 NOTE: The data set WORK.MBRTEST has 2 observations and 3 variables. NOTE: DATA statement used (Total process time): real time 0.01 seconds cpu time 0.00 seconds 17 ; 18 Run; First: do not place the ; at the end of datalines on a line with data, that causes an error. Your code did not provide any instructions on how to read Effedate so SAS assumes it is a simple numeric value. The / in the value means the values are not simple numbers and generate invalid data messages. The log tells you that the name of the Format you attempted to use is invalid. (Hint: None of the SAS supplied date formats/informats use YYYY in the name. Or at least I haven't see one yet.) The note that Effedata is uninitialized should have been a clue that you have a spelling issue. ... View more