Thank you for your help ballardw.  The date variable is definitely a date and not character data type.  The missing data in this column is indicated by a (.) when I view the table work.hs, which is notation for missing numeric data.  Also, in my original post I noted that the query that correctly pulled the data used "date < 0" and I think this would have caused an error if the column contained character data.  As a final check, I used the DESCRIBE statement in PROC SQL to verify that the column is numeric.   I am happy that missing(date) worked but I still don't understand why.  The missing(date) syntax yields different results than "date is missing" or "date is null".  I am querying an Oracle database so I wonder if it has something to do with the way SAS and Oracle see missing data; maybe they don't see missing data the same way. ... View more