SAS YYMMDD10. works but YYMMDDn10 doesn't - sql

Question

This is my data (sorry for no script, it's just proc create table from mssql):
testdb.testtable
id - numeric
date_from - numeric (datetime from mssql)
date_to - numeric (datetime from mssql)
base_id - numeric
base_id2 - string (length 64)
What I tried to do was:
proc sql;
update testdb.testtable tt
set base_id2 = CATX('_',
('data from other table'),
put(datepart(date_from),yymmddn10.),
put(datepart(date_to),yymmddn10.),
put(base_id,z4.)
)
where (....)
;
quit;
And I get this error:
The width value for YYMMDDN is out of bounds. It should be between 2 and 8.
The width value for YYMMDDN is out of bounds. It should be between 2 and 8.
What I really don't understand is that when I use format with separators, YYMMDD10., it works.
When i run:
proc sql;
select datepart(date_from) format=yymmddn10. from testdb.testtable;
quit;
It returns 20191227 - It's great. When I run
proc sql;
select put(datepart(date_from),yymmddn10.) from testdb.testtable;
quit;
It fails with the same error.
What do I miss?

Answer 1

There seems to be a bug in PROC SQL that allows you to attach a format that cannot work (the maximum width needed for a date without separators is 8 bytes).
It is also interesting that PROC PRINT (and the simple SELECT query in PROC SQL, like in your example) do not mind that the format width is invalid.
542 data test1;
543 now=date();
544 run;
NOTE: The data set WORK.TEST1 has 1 observations and 1 variables.
545
546 data test2 ;
547 set test1;
548 format now yymmddn10.;
----------
29
ERROR 29-185: Width specified for format YYMMDDN is invalid.
549 run;
NOTE: The SAS System stopped processing this step because of errors.
WARNING: The data set WORK.TEST2 may be incomplete. When this step was stopped there were 0 observations
and 1 variables.
WARNING: Data set WORK.TEST2 was not replaced because this step was stopped.
550
551 proc sql;
552 create table test2 as select now format=yymmddn10. from test1;
NOTE: Table WORK.TEST2 created, with 1 rows and 1 columns.
553 select * from test2;
554 quit;
555
556 proc print data=test2;
557 run;
NOTE: There were 1 observations read from the data set WORK.TEST2.
558
559 data test3;
560 set test2;
561 run;
ERROR: Width specified for format YYMMDDN is invalid.
NOTE: The SAS System stopped processing this step because of errors.
WARNING: The data set WORK.TEST3 may be incomplete. When this step was stopped there were 0 observations
and 1 variables.
WARNING: Data set WORK.TEST3 was not replaced because this step was stopped.
Also interesting is that if you use that format specification in PROC FREQ
proc freq data=test2; tables now; run;
it adds a space and a 'F7'x character in front of the data string.
The FREQ Procedure
Cumulative Cumulative
now Frequency Percent Frequency Percent
---------------------------------------------------------------
÷20200218 1 100.00 1 100.00

Answer 2

The number in format is the given width. Format YYMMDDn has 8 chars, so I should have used YYMMDDn8. And it worked.
I was having a long struggle with it and I still don't understand why did it work in format= and not in put().