I am converting a SAS script to Python, where the SAS script was interfacing with an Oracle database, and the Python will be interfacing with a PostgreSQL database. In the S
In SAS Missing values for numeric variables (including date variables) appear as a period. SAS treats numeric nulls as equal to “the lowest possible number” (essentially negative infinity) when sorting a numeric field.
SAS datasets will have a period as a value for missing data. When you export the data as CSV using proc export, I believe it will create a null value. To really answer your question you will need to know how the ETL from sasdata set to the current database was done.
I expect your data has been normalized for your database. Because of this I think you should use "IS NULL" in place of a "varname = '.' " . See below:
create table table_name as
select distinct wtn
from another_table
where account is NULL
;
In addition SAS Missing values for character variables appear as blanks. Missing values are set like this for character: if name="none" then name=' '.