Btw, you should < on date/datetime, not <=, as below. Otherwise you risk missing rows, especially if the data type of the underlying column changes (to datetime from smalldate, datetime2 from datetime, etc.).

Also, 'YYYYMMDD' is the only 100% safe date format (excluding obscure versions with 'T' in them).

ath_postdate >= '20130101' and

ath_postdate < '20130106'

Edit: I'm assuming it was Jan 05 not May 01 (demonstrating the ambiguity of the other format :-)).